chore(ci): create workflow to check the FrontMatter information in markdown

[lucaaamaral]

Problem

Docussaurus builds the sidebar according to the directory structure, detecting markdown files and listing the pages accordingly.
Docussaurus uses FrontMatter information to add the page's title and metadata.
We have a file sidebars.json with a list of files, check that is being used by the check_sidebars.py script.

Solution

Check if sidebars.json and if the check_sidebars.py is relevant, remove if not, document if it is.
Bring a CI check for presence and conformance of the FrontMatter header.

Non-goals

[lucaaamaral]

Although the workflow introduced by #13 checks for reference to new files, we still do not have a way of checking on pre-existing ones.

Suggestion: modify this script, adding the possibility to run locally against all markdown files.

[see7e]

Although the workflow introduced by #13 checks for reference to new files, we still do not have a way of checking on pre-existing ones.

Suggestion: modify this script, adding the possibility to run locally against all markdown files.

This is adressed at #14

PR closed due to replacement of the script with Docusaurus own sasnity checks and additional Markdown linters.