docs(readme): set descriptive title; drop tracking-issue reference (#15)

- Title is now "Syntax Highlighting in Etherpad" rather than just the
  package name, so the GitHub repo card / npm overview reads as a
  human-facing description.
- Drop the "Closes ether/etherpad#6616" line — that's PR-description
  copy that landed in the README by mistake and rots over time.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: JohnMcLear

README.md

@@ -1,6 +1,6 @@
-# ep_hljs
+# Syntax Highlighting in Etherpad
 
-Whole-pad syntax highlighting for Etherpad, powered by [highlight.js](https://highlightjs.org/). Closes [ether/etherpad#6616](https://github.com/ether/etherpad/issues/6616).
+Whole-pad syntax highlighting for [Etherpad](https://etherpad.org/), powered by [highlight.js](https://highlightjs.org/).
 
 ![Demo](demo.gif)