Update for auth.md for refresh token and support to mermaid charts in pdf

[offtherailz]

Description

In order to fix #10655 we need to update a chart in the documentation.
In the past, to support PDF export, a solution found was to convert all the charts, written in mermaid language (language widely supported by github, mkdocs and many other applications) in images.
This makes the documentation a lot less maintainable and reduces a lot the effeicency of creting them or updating.
For this reason, with this PR I restored the original charts code, and coverted the images using mkdocs-kroki-plugin. A plugin should that transformas mermaid charts into images.

The plugin above is base on Kroki that is a free service online, that provides also the possibility of self hosting services, whenever needed.

In the PR I:

• Included the kroki plugin
• Added some custom CSS to render properly the charts, without overflowing the pages
• Applied the effective changes here
• Add some minor fixes and doc. In detail:
  • Fixed position of the acon in note/warning sections
  • documented better the library installation for mkdocs, using the virtual env, and properly adding to .gitignore the folders generated by these commands
  • some minor typo fixes in mkdocs and improved doc.

Things to do:

• Test real documentation (not only PDF)
• Properly style pdf to set max-height of charts
• Get back old mermaid charts syntax
• Update the chart for auth.md with refresh token request

Note. This could be valid also for 2024.02.01, because it specifies the effective behavior even before the PR on geostrore mentioned in #10655

Please check if the PR fulfills these requirements

• The commit message follows our guidelines: https://github.com/geosolutions-it/MapStore2/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce? (check one with "x", remove the others)

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

Issue

What is the current behavior?

#10655 #10666

What is the new behavior?

Breaking change

Does this PR introduce a breaking change? (check one with "x", remove the other)

• Yes, and I documented them in migration notes
• No

Other useful information