feat: enable blink signature

Signed-off-by: Lander Van den Bulcke <landervandenbulcke@gmail.com>

config/plugins/cmp/cmp.nix

@@ -2,6 +2,19 @@
   plugins = {
     blink-cmp = {
       enable = true;
+      settings = {
+        signature = {
+          enabled = true;
+          trigger = {
+            enabled = true;
+            show_on_keyword = true;
+            show_on_insert = true;
+          };
+          window = {
+            show_documentation = true;
+          };
+        };
+      };
     };
   };
 }