[llvm] [Docs] Migrate LLVM docs to furo (PR #184440)

[Jeff Bailey via llvm-commits]

kaladron wrote:

Other things I've found myself wanting that you might consider if you're making deeper docs changes:

 * The sphinx tabs extension to be able to have different tabs depending on whether someone wants something for a particular architecture.
 * The ability to select some radio buttons and dropdowns for things like Release Builds which could alter what's in a code block.  I would like to make it easy to select a few options and then cut and paste.

Right now we do things like this:

https://libc.llvm.org/full_cross_build.html#cmake-configure-step

Where I have someone set a bunch of variables up front so that the rest is easy to cut and paste.  But it would be nice to make that a bit more elegant.


https://github.com/llvm/llvm-project/pull/184440