remove reference to Lua 5.2

Lua 5.1 is the target version and the extensions may or may not be
enabled at compile time.

README.md

@@ -26,7 +26,7 @@ If you are not already familiar with the language, there are plenty of resources
 
 It should also be noted that Lua is a very clean and simple language. It is easy to learn, especially if you have experience with similar scripting languages like JavaScript. You may already know more Lua than you realise!
 
-Note: the version of Lua that Neovim embeds is [LuaJIT](https://staff.fnwi.uva.nl/h.vandermeer/docs/lua/luajit/luajit_intro.html) 2.1.0, which maintains compatibility with Lua 5.1 (with a few 5.2 extensions).
+Note: the version of Lua that Neovim embeds is [LuaJIT](https://staff.fnwi.uva.nl/h.vandermeer/docs/lua/luajit/luajit_intro.html) 2.1.0, which maintains compatibility with Lua 5.1.
 
 ### Existing tutorials for writing Lua in Neovim
 

doc/nvim-lua-guide.txt

@@ -45,8 +45,7 @@ languages like JavaScript. You may already know more Lua than you realise!
 
 Note: the version of Lua that Neovim embeds is  LuaJIT:
 https://staff.fnwi.uva.nl/h.vandermeer/docs/lua/luajit/luajit_intro.html
-2.1.0, which maintains compatibility with Lua 5.1  with a few 5.2
-extensions .
+2.1.0, which maintains compatibility with Lua 5.1.
 
 Existing tutorials for writing Lua in Neovim~