doc(README): add lua

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

README.md

@@ -25,8 +25,10 @@ Requirements
 - [CMake](http://www.cmake.org)
 - [GMP (GNU multiprecision library)](http://gmplib.org/)
 - [MPFR (GNU MPFR Library)](http://www.mpfr.org/)
+- [Lua 5.2 or 5.1](http://www.lua.org), or [LuaJIT 2.0](http://luajit.org)
 - (optional) [gperftools](https://code.google.com/p/gperftools/)
 
+
 Installing required packages at
 --------------------------------
 

doc/make/ubuntu-12.04-detailed.md

@@ -8,6 +8,7 @@ Preparing working environment on Ubuntu 12.04
     sudo apt-get install libmpfr-dev
     sudo add-apt-repository ppa:kalakris/cmake -y
     sudo apt-get install cmake
+    sudo apt-get install liblua5.2.0 lua5.2-0 lua5.2-dev
 
     sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y
     sudo update-alternatives --remove-all gcc

doc/make/ubuntu-12.04.md

@@ -8,6 +8,9 @@ Instructions for installing gperftools on Ubuntu
     sudo apt-get dist-upgrade
     sudo apt-get install libgoogle-perftools-dev
 
+Instructions for installing Lua 5.2
+    sudo apt-get install liblua5.2.0 lua5.2-0 lua5.2-dev
+
 Instructions for installing gcc-4.8 (C++11 compatible) on Ubuntu
 
     sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y