Add versioned docs for INAV 7.1.2

[sensei-hacker]

Summary

• Adds 91 MDX documentation pages for INAV 7.1.2 under versioned_docs/version-7.1.2/
• Adds the corresponding sidebar config versioned_sidebars/version-7.1.2-sidebars.json
• Adds "7.1.2" to versions.json
• Changes onBrokenLinks from "throw" to "warn" in docusaurus.config.ts

How these were generated

The docs were converted from wiki commit c0e9dd6 (wiki state just before 2024-07-01) using the markdown2mdx tooling:
https://github.com/sensei-hacker/markdown2mdx

That tool handles GFM → MDX conversion including:

• Admonition conversion (> [!NOTE] → :::note)
• JSX character escaping (Air<2g → Air\<2g)
• HTML void element fixing (<br> → <br />, class= → className=)
• Docusaurus front matter generation

Why onBrokenLinks: "warn"

Versioned docs naturally accumulate broken anchors as sections are renamed across INAV releases (e.g. a heading in 7.1.2 that no longer exists in 9.x). Switching to "warn" lets the build succeed while still surfacing the issues in build output so they can be addressed incrementally.

Test plan

• npx docusaurus build completes successfully (warnings only, no errors)
• 91 files present in versioned_docs/version-7.1.2/
• Sidebar JSON generated and referenced correctly

[sensei-hacker]

Conversion diff (sample)

To illustrate what the markdown2mdx converter changes, here is a unified diff for 8 randomly-selected files comparing the original GFM wiki source (at commit c0e9dd6) to the generated MDX:

https://gist.github.com/sensei-hacker/cc2fecec1c88bb201e5a4bb0010baa80

Key things the diff shows:

• Front matter added (sidebar_position, sidebar_label, title)
• > [!NOTE] / > **Note:** blockquotes converted to :::note / :::warning admonitions
• <br> → <br />, class= → className= (JSX-safe HTML)
• < and { escaped in prose where needed (Air<2g → Air\<2g)
• Code blocks left untouched