Make :Rg within neovim smart by default

Enable --smart-case of rg by default.
That allows me to search for email finding Email and email.
While searching for Email only will find Email.

home/programs/neovim.nix

@@ -239,7 +239,13 @@ in {
 
     # Adding features
 
-    rg
+    {
+        plugin = rg;
+        config = ''
+          let g:rg_command = 'rg --vimgrep --smart-case'
+        '';
+    }
+
     diff-fold
     BufOnly-vim