Updated the file structure content because it was out of date. Pulled some out into a preamble, but ideally the preamble for this doc should be a summary of the doc types like the one proposed in #26389 (& I might do that as a follow up PR).

Reorganize the documentation docs structure a drop to remove the miscellaneous section, as roughly discussed in #28578

• "move documentation" moved under "write ReST" since it's mostly instructions on using a directive (like most of the content under write rest)
• "navbar and style" moved under "overview" since it's also a "how to find things"
• pulled out build into stand alone section w/ "options" and "show" as subsections

PR summary

PR checklist

• "closes #0000" is in the body of the PR description to link the related issue
• new and changed code is tested
• Plotting related features are demonstrated in an example
• New Features and API Changes are noted with a directive and release note
• Documentation complies with general and docstring guidelines