Merge pull request #6089 from Rob--W/README-crx-not-experimental

Update README (Chrome & Opera section)

README.md

@@ -37,16 +37,13 @@ PDF.js is built into version 19+ of Firefox, however one extension is still avai
 
 #### Chrome and Opera
 
-The Chromium extension is still somewhat experimental but it can be installed two
++ The official extension for Chrome can be installed from the [Chrome Web Store](https://chrome.google.com/webstore/detail/pdf-viewer/oemmndcbldboiebfnladdacbdfmadadm).
-ways:
+*This extension is maintained by [@Rob--W](https://github.com/Rob--W).*
-
++ Opera has also published an extension for their browser at the [Opera add-ons catalog](https://addons.opera.com/en/extensions/details/pdf-viewer/).
-+ [Unofficial Version](https://chrome.google.com/webstore/detail/pdf-viewer/oemmndcbldboiebfnladdacbdfmadadm) - *This extension is maintained by a PDF.js contributor.*
 + Build Your Own - Get the code as explained below and issue `node make chromium`. Then open
 Chrome, go to `Tools > Extension` and load the (unpackaged) extension from the
 directory `build/chromium`.
 
-The version of the extension for the Opera browser can be found at the [Opera add-ons catalog](https://addons.opera.com/en/extensions/details/pdf-viewer/).
-
 ## Getting the Code
 
 To get a local copy of the current code, clone it using git: