drop Opera support

I neither care nor have time to publish new updates for it.

Author: sindresorhus

readme.md

@@ -1,16 +1,16 @@
 # Show All GitHub Issues
 
-> Chrome/Opera extension - Show both Issues and Pull Requests in the Issues tab by default. As it previously did.
+> Chrome extension - Show both Issues and Pull Requests in the Issues tab by default. As it previously did.
 
 ![](screenshot.png)
 
 
 ## Install
 
-* [Chrome extension](https://chrome.google.com/webstore/detail/show-all-github-issues/ahkcgmpcfiijldaijfjekdffckpidieb)
-* [Opera add-on](https://addons.opera.com/en/extensions/details/github-issues-all/)
+Install it from the [Chrome Web Store](https://chrome.google.com/webstore/detail/show-all-github-issues/ahkcgmpcfiijldaijfjekdffckpidieb) or [manually](http://superuser.com/a/247654/6877).
+## Install
 
 
 ## License
 
-MIT © [Sindre Sorhus](http://sindresorhus.com)
+MIT © [Sindre Sorhus](https://sindresorhus.com)