completion: support non ascii with cmp-buffer

- Supports non ASCII chars in text completion (cmp-buffer).
- Restore the luasnip configuration inside the nvim-cmp configuration,
  as it is indeed closely related. I didn't understood it in the first
  place.

Co-Authored-by: iGor milhit <igor@milhit.ch>

init.lua

@@ -547,7 +547,9 @@ mason_lspconfig.setup_handlers {
   end,
 }
 
--- [[ Configure LuaSnip ]]
+-- [[ Configure nvim-cmp, and LuaSnip ]]
+-- See `:help cmp`
+local cmp = require 'cmp'
 local luasnip = require 'luasnip'
 require('luasnip.loaders.from_vscode').lazy_load()
 luasnip.config.setup {
@@ -566,10 +568,6 @@ require("luasnip.loaders.from_lua").load({paths = "~/.config/nvim/my_snippets/"}
 --   https://www.ejmastnak.com/tutorials/vim-latex/luasnip/#refreshing-snippets-from-a-separate-vim-instance
 vim.keymap.set('n', '<Leader>L', '<Cmd>lua require("luasnip.loaders.from_lua").load({paths = "~/.config/nvim/my_snippets/"})<CR>', { desc = 'Reload [L]uaSnippets' })
 
--- [[ Configure nvim-cmp ]]
--- See `:help cmp`
-local cmp = require 'cmp'
-
 cmp.setup {
   snippet = {
     expand = function(args)
@@ -611,6 +609,7 @@ cmp.setup {
       name = 'buffer',
       option = {
         keyword_length = 4,
+        keyword_pattern = [[\k\+]],
       },
     },
     { name = 'luasnip' },