Updates page templates and updates GitHub labels (#5279)

Updates page template formats and substitutes new GitHub labels. Fixes
#5268

---------

Co-authored-by: Parker Lougheed <parlough@gmail.com>

Author: atsansone

.github/ISSUE_TEMPLATE/1_page_issue.yml

@@ -1,42 +1,66 @@
 name: Page issue
-description: Help improve a dart.dev page
+description: Help improve the content or quality of a dart.dev page
+labels: [from.page-issue]
 body:
   - type: markdown
     attributes:
       value: |
-          _Found a typo? You can fix it yourself by going to the page source and clicking the pencil icon. Or finish creating this issue._
+          Found a typo? You can fix it yourself!
+
+          1. Click the page icon to the left of the bug icon you clicked to come to this form. The GitHub page source should display.
+          1. Click the pencil icon displayed above the source code.
+          1. Fix the typo.
+          1. Click **Commit changes...**.
+          1. Update the commit message and add a description.
+          1. Click **Propose changes**.
+
+          If you want another contributor to fix this issue, complete this form.
   - type: input
     id: page-url
     attributes:
       label: Page URL
-      placeholder: "Example: https://dart.dev/guides"
+      placeholder: "Add the address of this page. An example would be https://dart.dev/guides"
     validations:
       required: true
   - type: input
     id: page-source
     attributes:
       label: Page source
-      placeholder: (Provided automatically by the in-page bug link)
+      placeholder: The bug link provides this information.
     validations:
       required: false
   - type: textarea
     id: problem
     attributes:
       label: Describe the problem
-      placeholder: A clear and concise description of what's wrong.
+      placeholder: Provide a clear and concise description of you believe to be in error.
     validations:
       required: true
   - type: textarea
     id: fix
     attributes:
       label: Expected fix
-      placeholder: A clear and concise description of how you think we should fix the problem.
+      placeholder: Provide a clear and concise description of how you think this problem should be fixed.
     validations:
       required: false
   - type: textarea
     id: additional-info
     attributes:
       label: Additional context
-      placeholder: Anything else we should know about the problem?
+      placeholder: |
+        Provide anything else that should be known about the problem. 
+        This could include:
+
+        * when in your workflow this occurred
+        * what platform and browser you are using
+        * other configuration or circumstantial information that you think could impact fixing your issue
     validations:
       required: false
+  - type: checkboxes
+    id: volunteer
+    attributes:
+      label: I would like to fix this problem.
+      description: Let us know if you want to try fixing this yourself.
+      options:
+        - label: I will try and fix this problem on dart.dev.
+          required: false

.github/ISSUE_TEMPLATE/2_topic_request.yml

@@ -1,18 +1,26 @@
 name: Topic request
 description: What information should be on dart.dev but isn't covered well (or at all)?
-labels: [new page/topic request]
+labels: [co.request, from.user]
 body:
   - type: textarea
     id: problem
     attributes:
-      label: What information is missing?
-      placeholder: A clear and concise description of what you expected to find on dart.dev, but didn't.
+      label: What information needs to be added?
+      placeholder: Provide a clear and concise description of what you expected to find on dart.dev, but didn't.
     validations:
       required: true
   - type: textarea
     id: fix
     attributes:
-      label: How would you like us to fix this problem?
-      placeholder: Let us know where you'd expect to see this missing information.
+      label: Where should this new content appear?
+      placeholder: Let us know where you'd expect to see this new information.
     validations:
       required: false
+  - type: checkboxes
+    id: volunteer
+    attributes:
+      label: I would like to fix this problem.
+      description: Let us know if you want to try fixing this yourself.
+      options:
+        - label: I will try and fix this problem on dart.dev.
+          required: false

.github/ISSUE_TEMPLATE/3_design_issue.yml

@@ -1,25 +1,44 @@
-name: Site appearance or accessibility issue
-description: How can we improve the CSS or page design of dart.dev?
-labels: [design]
+name: Site design or user experience issue
+description: How can we improve the page design, style, or structure of dart.dev?
+labels: [infra.design, from.user]
 body:
   - type: textarea
     id: problem
     attributes:
       label: Describe the problem
-      placeholder: A clear and concise description of the issue, preferably with a screenshot.
+      placeholder: Provide a clear and concise description of the issue. What did you expect to happen? Screenshots are recommended.
     validations:
       required: true
   - type: textarea
     id: fix
     attributes:
       label: Expected fix
-      placeholder: A clear and concise description of how you think we should fix the problem.
+      placeholder: Provide a clear and concise description of how you think this problem should be fixed.
     validations:
       required: false
+  - type: dropdown
+    id: platform
+    attributes:
+      label: On which browser(s) did you experience this issue?
+      multiple: true
+      options:
+        - Firefox
+        - Chrome
+        - Safari
+        - Microsoft Edge
+        - Other
   - type: textarea
     id: additional-info
     attributes:
       label: Additional context
-      placeholder: Helpful examples, screenshots, or descriptions go here. If you're interested in helping us fix the issue, let us know!
+      placeholder: Provide examples, screenshots, configurations, or descriptions that could help.
     validations:
       required: false
+  - type: checkboxes
+    id: volunteer
+    attributes:
+      label: I would like to fix this problem.
+      description: Let us know if you want to try fixing this yourself.
+      options:
+        - label: I will try and fix this problem on dart.dev.
+          required: false

.github/ISSUE_TEMPLATE/4_infrastructure.yml

@@ -1,22 +1,32 @@
 name: Site infrastructure issue
 description: |
-    Report a problem with the build, repo, or something else that's a problem for people who work on dart.dev
-labels: [infrastructure]
+    Report a problem with the build, repo, or tooling for dart.dev
+labels: [infra.structure, from.user]
 body:
   - type: textarea
     id: problem
     attributes:
       label: Describe the problem
-      placeholder: A clear and concise description of the issue.
+      placeholder: Provide a clear and concise description of the issue. What did you expect to happen? Screenshots are recommended.
     validations:
       required: true
   - type: textarea
     id: fix
     attributes:
       label: Expected fix
-      placeholder: A clear and concise description of how you think we should fix the problem.
+      placeholder: Provide a clear and concise description of how you think this problem should be fixed.
     validations:
       required: false
+  - type: dropdown
+    id: platform
+    attributes:
+      label: On which platform(s) did you experience this issue?
+      multiple: true
+      options:
+        - macOS
+        - Windows
+        - Linux
+        - ChromeOS
   - type: textarea
     id: additional-info
     attributes: