doc(readme): add luajit requirement (#2738)

Author: Conni2461

README.md

@@ -44,6 +44,8 @@ This section should guide you to run your first builtin pickers.
 
 [Neovim (v0.9.0)](https://github.com/neovim/neovim/releases/tag/v0.9.0) or the
 latest neovim nightly commit is required for `telescope.nvim` to work.
+The neovim version also needs to be compiled with LuaJIT, we currently do not
+support Lua5.1 because of some ongoing issues.
 
 ### Required dependencies