Added prerequisites to index.html

docs/index.html

@@ -55,6 +55,16 @@ iceprog rot.bin</pre>
 
 <h2>Where are the Tools? How to install?</h2>
 
+<p>
+Installing prerequisites (this command is for Ubuntu 14.04):
+</p>
+
+<pre style="padding-left: 3em">
+sudo apt-get install build-essential clang bison flex libreadline-dev \
+                     gawk tcl-dev libffi-dev git mercurial graphviz   \
+                     xdot pkg-config python libftdi-dev
+</pre>
+
 <p>
 Installing the <a href="https://github.com/cliffordwolf/icestorm">IceStorm Tools</a> (icepack, icebox, iceprog):
 </p>