tuning cmp cmdline and search

lua/plugins/cmp.lua

@@ -160,7 +160,8 @@ return {
     })
 
     -- Use buffer source for `/` (if you enabled `native_menu`, this won't work anymore).
-    cmp.setup.cmdline('/', {
+    cmp.setup.cmdline({ '/', '?' }, {
+      mapping = cmp.mapping.preset.cmdline(),
       sources = {
         { name = 'buffer' },
       },
@@ -168,12 +169,14 @@ return {
 
     -- Use cmdline & path source for ':' (if you enabled `native_menu`, this won't work anymore).
     cmp.setup.cmdline(':', {
-      sources = {
+      mapping = cmp.mapping.preset.cmdline(),
+      sources = cmp.config.sources({
         { name = 'cmdline' },
         -- { name = 'cmdline_history' },
         { name = 'path' },
         { name = 'buffer' },
-      },
+      }),
+      matching = { disallow_symbol_nonprefix_matching = false },
     })
 
     require('cmp').setup.filetype({ 'dap-repl', 'dapui_watches', 'dapui_hover' }, {