Use `cmp-nvim-lua` as `nvim-cmp` source for neovim Lua API (#696)

* Use cmp-nvim-lua as nvim-cmp source for neovim Lua API

* Move the dependency to a more suitable place

init.lua

@@ -640,6 +640,9 @@ require('lazy').setup({
       --  into multiple repos for maintenance purposes.
       'hrsh7th/cmp-nvim-lsp',
       'hrsh7th/cmp-path',
+      -- nvim-cmp source for neovim Lua API
+      -- so that things like vim.keymap.set, etc. are autocompleted
+      'hrsh7th/cmp-nvim-lua',
 
       -- If you want to add a bunch of pre-configured snippets,
       --    you can use this plugin to help you. It even has snippets
@@ -701,6 +704,7 @@ require('lazy').setup({
           end, { 'i', 's' }),
         },
         sources = {
+          { name = 'nvim_lua' },
           { name = 'nvim_lsp' },
           { name = 'luasnip' },
           { name = 'path' },