Fix link

Author: koutcher

README.adoc

@@ -25,8 +25,7 @@ Resources
 
 Bugs and Feature Requests
 -------------------------
-Please check out the
-https://github.com/jonas/tig/blob/master/TROUBLESHOOTING.adoc[troubleshooting guide]
+Please check out the link:TROUBLESHOOTING.{docext}[troubleshooting guide]
 if you are experiencing issues with Tig.
 
 Bugs and feature requests can be reported using the