add lua doc in Installion.mainpage

doc/pages/Installation.mainpage

@@ -14,6 +14,7 @@ On debian, depending on the interface you want, install the package(s)
 \verbatim
 libshogun-dev         - for C++ developers building extensions using
                         libshogun
+shogun-lua-modular    - for the modular lua interface
 shogun-java-modular   - for the modular java interface
 shogun-octave         - for the static octave interface
 shogun-octave-modular - for the modular octave interface
@@ -69,6 +70,9 @@ CPLEX(tm) just make sure cplex can be found in the PATH. If it is not found
 shogun will resort to GLPK (if version at least 4.29 is found) for 1-norm MKL,
 p-norm MKL with p>1 will work nonetheless.
 
+\li To compile the Lua interface you need to have the Lua developer files 
+(debian package lua) installed.
+
 \li To compile the Java interface you need to have the Java developer files 
 (debian package openjdk-6-jdk) installed.
 
@@ -109,6 +113,8 @@ where \b interface is one of the following
 
 \li java_modular -- for java (see http://www.java.com).
 
+\li lua_modular -- for lua (see http://www.lua.org).
+
 \li matlab -- for matlab (see http://www.mathworks.com)
 
 (you don't need to compile libshogunui in case you compile a modular interface)