docs: Fix URL links in markdown.

Author: microbit-carlos

docs/contributing.md

@@ -16,7 +16,7 @@ into the GitHub issue tracker to see what is available. Planned features are
 marked with the "enhancement" label, and know issues are marked with the "bug"
 label.
 
-https://github.com/microbit-foundation/microbit-universal-hex/issues
+[https://github.com/microbit-foundation/microbit-universal-hex/issues](https://github.com/microbit-foundation/microbit-universal-hex/issues)
 
 If you're interested in working on any of these items, please respond to an
 existing issue, or file a new one, and mention @microbit-carlos.

docs/quick-guide.md

@@ -8,7 +8,9 @@ nav_order: 2
 
 ## ES5 UMD Bundle
 
-Download the UMD bundle from a GitHub release and add it to the page:
+Download the UMD bundle from the
+[latest GitHub release](https://github.com/microbit-foundation/microbit-universal-hex/releases/latest)
+and add it to the page:
 
 ```html
 <script src="microbit-uh.umd.min.js"></script>
@@ -44,6 +46,6 @@ separatedBinaries.forEach(function (hexObj) {
 ## npm package
 
 You can integrate this library in your project using the npm package:
-https://www.npmjs.com/package/@microbit/microbit-universal-hex
+[https://www.npmjs.com/package/@microbit/microbit-universal-hex](https://www.npmjs.com/package/@microbit/microbit-universal-hex)
 
 For information on how to use this library check the API documentation.