[llvm-branch-commits] [llvm] [docs] Rewrite SphinxQuickstartTemplate.md in MyST Markdown (PR #198896)

[Jonas Devlieghere via llvm-branch-commits]

https://github.com/JDevlieghere approved this pull request.

I left one inline suggestion, but otherwise this LGTM.

https://github.com/llvm/llvm-project/pull/198896