Add initial README

Signed-off-by: Danila Fedorin <daniel.fedorin@hpe.com>

Author: DanilaFe

README.md

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+# Introduction to Chapel
+
+[Chapel](https://chapel-lang.org/) is a programming language for productive parallel computing. This repository contains code from the [ChapelCon 2024](https://chapel-lang.org/ChapelCon24.html) Chapel tutorial.
+
+To get started with this template, you can either use [GitHub Codespaces](#using-a-codespace) or your own machine (via [Docker](#using-docker) or by [building from source](#building-chapel-from-source-on-your-machine)).
+
+The files in this repository correspond to files in the tutorial slide deck.
+They are listed with numerical prefixes (e.g., `01-heat-1D-serial.chpl`)
+that represent the order in which they appear in the slides.
+
+## Learning Resources
+To learn about Chapel beyond what's presented in the slides, consider the
+following resources:
+
+* For Chapel’s core features, check out the [Advent of Code](https://chapel-lang.org/blog/series/advent-of-code-2022/) blog series
+* For more information on Chapel’s various loops, including ‘forall’, check out the [Loops primer](https://chapel-lang.org/docs/primers/loops.html)
+* For details on Chapel's GPU support, see [Introduction to GPU Programming](https://chapel-lang.org/blog/posts/intro-to-gpus/)
+
+For a broader list of resources, check out the [Learning Chapel](https://chapel-lang.org/learning.html) page on the Chapel website.
+
+## Using a Codespace
+
+> :warning: Because Codespaces are a virtualized environment running on shared hardware with a modest core count, don't expect parallelism or performance observed here to be reflective of what a native installation of Chapel can achieve.
+
+This repo includes a `devcontainer.json` file, making it usable from GitHub Codespaces. When viewing this repository from GitHub's UI, click __Use this template > Open in a codespace__ to get started. The codespace includes the Visual Studio Code extension for Chapel, and tools such as [`chpl-language-server`](https://chapel-lang.org/docs/main/tools/chpl-language-server/chpl-language-server.html) and [`chplcheck`](https://chapel-lang.org/docs/main/tools/chplcheck/chplcheck.html).
+
+In the Codespace, compile Chapel programs using the __Terminal__ tab by using the `chpl` compiler:
+
+```bash
+chpl 01-hello.chpl
+./01-hello
+```
+
+### Simulating Multiple Nodes
+Although the Codespace is set to a single-locale (single-node) mode by default, you can simulate multiple nodes by setting the `CHPL_COMM` environment variable to `gasnet` when compiling.
+
+```bash
+# Compile a program that distributes computation to multiple nodes
+CHPL_COMM=gasnet chpl 01-hellopar.chpl
+
+# Run hello using two simulated nodes
+./01-hellopar -nl 2
+```
+
+To avoid having to include `CHPL_COMM` in each compilation command, you can
+`export` it:
+
+```bash
+export CHPL_COMM=gasnet
+chpl 01-hellopar.chpl
+./01-hellopar -nl 2
+```
+
+### Simulating GPU Support
+GitHub codespaces do not have GPUs available to them. However, Chapel
+provides a mode called ["CPU-as-device"](https://chapel-lang.org/docs/technotes/gpu.html#cpu-as-device-mode),
+which mocks GPU support by running GPU-eligible loops on the CPU. To enable
+this mode, set the `CHPL_LOCALE_MODEL` to `gpu` (to enable GPU support)
+and `CHPL_GPU` to `cpu` to select "CPU-as-device" mode.
+
+```bash
+CHPL_LOCALE_MODEL=gpu CHPL_GPU=cpu chpl 01-hellopar.chpl
+```
+
+## Using Docker
+
+Install Docker (see the [Installing Docker](#installing-docker) section below for suggestions). Then, use the following command:
+
+```bash
+docker pull docker.io/chapel/chapel-gasnet
+```
+
+Next follow the instructions at https://hub.docker.com/r/chapel/chapel to compile a hello world in Chapel, but use the `chapel-gasnet` container and when you run the “hello” executable specify `-nl 1`.  Here are the commands to use:
+
+```
+echo 'writeln("Hello, world!");' > hello.chpl
+
+docker run --rm -it -v "$PWD":/myapp -w /myapp chapel/chapel-gasnet /bin/bash
+
+root@xxxxxxxxx:/myapp# chpl hello.chpl
+root@xxxxxxxxx:/myapp# ./hello -nl 1
+Hello, world!
+```
+
+Note that the Chapel docker image with GASNet support does not have
+any GPU-related support. To use GPU support, you might be better served
+by [building from source](#building-chapel-from-source-on-your-machine) on
+your own machine.
+
+## Building Chapel from Source on Your Machine
+
+Please follow the instructions on the [Download Chapel](https://chapel-lang.org/download.html) page to build the Chapel compiler and runtime from source and get set up with the Chapel compiler executable `chpl`. From there, you can compile and run the `01-hello.chpl` file in this repository as follows:
+
+```bash
+chpl 01-hello.chpl
+./01-hello
+```
+
+To make use of multiple nodes (or to simulate multi-node execution), please
+refer to [Multilocale Chapel Execution](https://chapel-lang.org/docs/usingchapel/multilocale.html).
+To set up for Chapel's GPU support, refer to the [GPU Programming](https://chapel-lang.org/docs/technotes/gpu.html) tech note.
+
+## Installing Docker
+
+### Mac
+
+Download the docker desktop for Intel or Arm as appropriate from
+https://docs.docker.com/get-docker/.
+
+Start up docker desktop.  You do not need a docker account.
+
+
+### Linux
+
+* First three steps on https://docs.docker.com/engine/install/ubuntu/
+  1. Set up Docker's Apt repository.
+    ```
+      # Add Docker's official GPG key:
+      sudo apt-get update
+      sudo apt-get install ca-certificates curl gnupg
+      sudo install -m 0755 -d /etc/apt/keyrings
+      curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
+      sudo chmod a+r /etc/apt/keyrings/docker.gpg
+
+      # Add the repository to Apt sources:
+      echo "deb [arch="$(dpkg --print-architecture)" signed-by=/etc/apt/keyrings/docker.gpg]   https://download.docker.com/linux/ubuntu "$(. /etc/os-release && echo "$VERSION_CODENAME")" stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
+      sudo apt-get update
+    ```
+
+  2. Install the Docker packages.
+    ```
+      sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
+    ```
+
+  3. Verify that the Docker Engine installation is successful by running the hello-world image.
+    ```
+      sudo docker run hello-world
+    ```
+
+
+* Additional steps
+    ```
+      sudo groupadd docker
+      sudo usermod -aG docker ${USER}
+
+      # maybe not necessary
+      sudo chmod 666 /var/run/docker.sock
+
+    ```
+
+### Windows
+
+1. download docker for windows from: https://docs.docker.com/desktop/install/windows-install/
+  a. when promted to log in or create an account, select continue without logging in
+
+2. open a Powershell terminal (preferably as admin)
+  a. if you don't have WSL installed, execute `wsl --install`
+  b. next, ensure that your Ubuntu distro is using WSL2 (rather than WSL1).
+  Execute `wsl -l -v` and ensure that ubuntu says 2 under version.
+   i. If it is on version 1, execute `wsl --set-version ubuntu 2` (may take some time)
+
+3. open the docker desktop app to start the docker daemon
+  a. you can check that docker is using WSL Ubuntu by going to
+  Settings > Resources > WSL Integration
+
+4. in Powershell, execute docker pull chapel/chapel-gasnet
+
+*NOTE*: For Windows you will probably have to replace the `$PWD` from the instructions
+at https://hub.docker.com/r/chapel/chapel with the Windows version of the current path
+written out