Added a minimum zsh version note.

README.textile

@@ -4,6 +4,8 @@ bq. "OH MY ZSHELL!"
 
 h2. Setup
 
+@oh-my-zsh@ should work with any recent release of "zsh":http://www.zsh.org/, the minimum recommended version is 4.3.9.
+
 h3. The automatic installer... (do you trust me?)
 
 @wget http://github.com/robbyrussell/oh-my-zsh/raw/master/tools/install.sh -O - | sh@