Update INSTALL.md

INSTALL.md

 # Pre-requisites #
 
-If you want to build the manpage, you will need ronn. Newer versions of Debian come with a package:
+If you want to build the manpage, you will need [ronn] [1].
+Debian 7.0 and above come with a package, so do most Debian clones.
+
+To install ronn on your Debian-based system, simply run
 
 	apt-get install ruby-ronn
 
+There are no other dependencies other than `git`, `ronn` and a POSIX shell.
+
 
 # Installing #
 
@@ -14,13 +19,15 @@ If you want to build the manpage, you will need ronn. Newer versions of Debian c
 
 	sudo make uninstall
 
-There is another, more thorough, version. Just make sure you are not running this when you have installed to an important directory which is empty, otherwise.
+There is another, more thorough, version. Just make sure you are not running
+this when you have installed to an important directory which is empty,
+otherwise.
 
-**THIS WILL DELETE /usr/local IF YOU INSTALLED THERE AND IT'S EMPTY, OTHERWISE**
+**THIS WILL DELETE /usr/local IF YOU INSTALLED THERE AND IT BECOMES EMPTY**
 
 	sudo make purge
 
-**THIS WILL DELETE /usr/local IF YOU INSTALLED THERE AND IT'S EMPTY, OTHERWISE**
+**THIS WILL DELETE /usr/local IF YOU INSTALLED THERE AND IT BECOMES EMPTY**
 
 This is not in the default behaviour of `make uninstall` for obvious reasons.
 
@@ -34,3 +41,5 @@ To clean up the generated manpage, run
 and if you are bored, I suggest
 
 	make moo
+
+[1]: http://rtomayko.github.io/ronn/