doc: installing pandoc added in contributing.md

Author: Henri-ColibrITD

CONTRIBUTING.md

@@ -18,7 +18,7 @@ describing the problem you would like to solve.
 
 ### Setup your environment locally
 
-_Some commands will assume you have the GitHub CLI installed, if you haven't,
+\_Some commands will assume you have the GitHub CLI installed, if you haven't,
 consider [installing it](https://github.com/cli/cli#installation), but you can
 always use the Web UI if you prefer that instead.
 
@@ -41,6 +41,13 @@ etc... included), use pip:
 pip install -r requirements-dev.txt
 ```
 
+In the documentation, some notebooks are rendered to HTML, this process is done
+using [Pandoc](https://pandoc.org/). Unfortunately, this software cannot be
+installed from the pip repository, so you need to install it separately. You can
+check [their documentation](https://pandoc.org/installing.html) to see how to
+install it on your OS (you can find it on most package manager: `apt`,
+`yum`, `pacman`, `choco`, `winget`, `brew` and more... )
+
 The last (optinal) step is to setup a GitHub personal access tokens to enable
 the sphinx automatic changelog generation. This step is only important if you
 want to preview this changelog generation on your personal computer. Not being

Dockerfile

@@ -9,9 +9,9 @@ RUN pip3 install --upgrade pip && \
 
 FROM python:3.9
 
-RUN apt-get update && \
-    apt-get install -y pandoc && \
-    apt-get clean && \
+RUN apt update && \
+    apt install -y pandoc && \
+    apt clean && \
     rm -rf /var/lib/apt/lists/*
 
 WORKDIR /usr/src/app/mpqp