neovim: add `caveats` for tree-sitter parsers. (#109966)
neovim: add `caveats` for tree-sitter parsers. (#109966)

See Homebrew/discussions#3611.

When 0.8 is released, we can bundle the parsers for `stable` builds, or
ship them as separate formulae and add them as dependencies. Given this,
it makes sense to restrict the `caveats` to `--HEAD` installs.
Homebrew/homebrew-core,chrisfinazzo/homebrew-core,stgraber/homebrew-core,stgraber/homebrew-core,adam-moss/homebrew-core,adam-moss/homebrew-core,nandub/homebrew-core,sjackman/homebrew-core,makigumo/homebrew-core,lemzwerg/homebrew-core,sjackman/homebrew-core,chrisfinazzo/homebrew-core,filcab/homebrew-core,makigumo/homebrew-core,filcab/homebrew-core,Homebrew/homebrew-core,lemzwerg/homebrew-core,nandub/homebrew-core