Add additional comment for context in Tyepscript highlights (#42564)
This adds additional comments which were left out from #42494 by
accident. Namely, it describes why we have additional custom
highlighting in `highlights.scm` for the Typescript grammar.
Release Notes:
- N/A
b403c199dfKyleBarton committed on 11/12/2025, 7:59:10 PM· committed by GitHubparentcb40677