Update README.MD

Add information on installation regarding Mono.

README.md

@@ -18,7 +18,7 @@ Windows users:
 Mac/Linux users:
 
 <ul>
-	<li>You need to install Mono if you haven't already. Please Google how to do that.</li>
+	<li>You need to install Mono if you haven't already. On Mac, install homebrew from https://brew.sh/, and type <pre>brew install mono</pre> in a Terminal window. In Linux, use your package manager (APT for Debian/Ubuntu, etc) and install the appropiate mono package - Google is your friend if you don't understand.</li>
 	<li>Open a command prompt (Terminal on Mac).</li>
 	<li>Type "cd" and put a space.</li>
 	<li>Drag and drop the folder with the patcher (it either says Mac or Linux depending on what you choose) to the command prompt.</li>