merge documentation change of #231 of @tndoan and resolve authors conflict

AUTHORS.txt

@@ -39,6 +39,7 @@ Arthur Jaron (@eyetracker)
 Justin M. Keyes (@justinmk)
 nagev (@np1)
 Chris Lasher (@gotgenes) <chris.lasher@gmail.com>
+Doan Thanh Nam (@tndoan)
 
 
 @something are github user names.

README.rst

@@ -80,6 +80,10 @@ Note that the `python-mode <https://github.com/klen/python-mode>`_ VIM plugin se
 to conflict with jedi-vim, therefore you should disable it before enabling
 jedi-vim.
 
+To enjoy the full features of Jedi-Vim, you should have VIM >= 7.3. For older 
+version of VIM, the parameter recommendation list maybe not appeared when you type
+open bracket after the function name.
+
 
 Settings
 ========

doc/jedi-vim.txt

@@ -82,6 +82,10 @@ using pip: >
 However, you can also install it as a git submodule if you don't want to use
 jedi for anything but this plugin. How to do this is detailed below.
 
+It is the best if you have VIM >= 7.3. For the older version, you probably 
+cannot see the parameter recommendation list of function after typing open 
+bracket.
+
 ------------------------------------------------------------------------------
 2.1. Installing manually		*jedi-vim-installation-manually*