added chrome link to readme

Author: ProCynic

README.md

@@ -4,6 +4,11 @@ Create github issues from trello cards.
 
 ## Installation
 
+### From Web store
+
+https://chrome.google.com/webstore/detail/trello-to-github-issue/mcdgcblepfepgcjfjmhhdhoapahpeaob
+
+### Manual
 1. Clone the repo.
 2. Open chrome and go to `chrome://extensions`
 3. Make sure Developer Mode is checked.