Update README.md
fixed ack.vim link
@@ -167,7 +167,7 @@ You may need to use `sudo` or run as root for the make install.
### Vim
-You can use Ag with [ack.vim][] by adding the following line to your `.vimrc`:
+You can use Ag with [ack.vim](https://github.com/mileszs/ack.vim) by adding the following line to your `.vimrc`:
let g:ackprg = 'ag --nogroup --nocolor --column'
