Add INAV 8.0.1 versioned docs

[sensei-hacker]

Summary

• Adds versioned_docs/version-8.0.1/ — complete INAV 8 wiki converted to Docusaurus MDX using the markdown2mdx/full_file converter
• Adds versioned_sidebars/version-8.0.1-sidebars.json
• Updates versions.json to include 8.0.1 as the current version
• Adds static/img/content/209.png referenced by the Custom OSD docs

The versioned docs include:

• 22 release notes (1.7.3 through 8.0.0 "Gallant Goshawk")
• advanced/ — 44 pages (advanced configuration, CLI variables, MSP, etc.)
• features/ — 7 pages (Failsafe, Modes, GPS failsafe, etc.)
• legacyinfo/ — 12 pages (legacy targets, old tuning guides)
• quickstart/ — 12 pages (getting started, guides, troubleshooting)

Conversions applied by the converter:

• >[!Note]/>[!Warning]/etc. → :::note/:::warning admonitions
• GitHub wiki links → relative Docusaurus paths
• GitHub image URLs → local /img/content/ paths
• [[double bracket]] wiki links resolved
• HTML void elements and class= → JSX-compatible <br />, className=
• _category_.json files generated for each subdirectory

Test plan

• Build Docusaurus site locally and verify no build errors
• Check version switcher shows 8.0.1 as an option
• Spot-check a few pages in each section render correctly
• Verify admonitions render (:::note, :::warning)