Feature/jk/docs

[JulesKouatchou]

Description

Created a new docs directory that has the following subdirectories:

• tutorial: what used to be a top directory (with the same content)
• user_guide: a new directory that will serve as MAPL User's Guide.

Related Issue

Motivation and Context

The changes are meant to create an area where all the documentation will be located.
Note that it does not include the documentation generated by FORD.

How Has This Been Tested?

No test was needed here. The changes produce 0 diff.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Trivial change (affects only documentation or cleanup)

Checklist:

• I have tested this change with a run of GEOSgcm (if non-trivial)
• I have added one of the required labels (0 diff, 0 diff trivial, 0 diff structural, non 0-diff)
• I have updated the CHANGELOG.md accordingly following the style of Keep a Changelog

[mathomp4]

I moved the base of this to develop, not main

[mathomp4]

@JulesKouatchou One more thing with this. Could you add to the main README.md with a link or something pointing to the new user guide? I suppose before the Contributing section maybe?