fix: error on addtional textedit(#157)

Author: haorenW1025

lua/completion.lua

@@ -67,7 +67,7 @@ end
 
 -- apply additionalTextEdits in LSP specs
 local function applyAddtionalTextEdits(completed_item)
-  local lnum = api.nvim_win_get_cursor(0)[0]
+  local lnum = api.nvim_win_get_cursor(0)[1]
   if completed_item.user_data.lsp ~= nil then
     local item = completed_item.user_data.lsp.completion_item
     -- vim-vsnip have better additional text edits...