Add link to third-party `JavaScript (JSX).tmLanguage` in docs.

docs/02.1-jsx-in-depth.md

@@ -162,10 +162,15 @@ var content = <Container>{/* this is a comment */}<Nav /></Container>;
 Beyond the compilation step, JSX does not require any special tools.
 
 * Many editors already include reasonable support for JSX (Vim, Emacs js2-mode).
+  * JSX syntax highlighting is available for Sublime Text and other editors
+    that support `*.tmLanguage` using the third-party
+    [`JavaScript (JSX).tmLanguage`][1].
 * Linting provides accurate line numbers after compiling without sourcemaps.
 * Elements use standard scoping so linters can find usage of out-of-scope
   components.
 
+[1]: https://github.com/yungsters/sublime/blob/master/tmLanguage/JavaScript%20(JSX).tmLanguage
+
 ## Prior Work
 
 JSX is similar to several other JavaScript embedded XML language