docs(readme): clarify mapping (#2723)

README.md

@@ -254,7 +254,7 @@ Many familiar mapping patterns are set up as defaults.
 | `<M-k>`        | Scroll right in results window                       |
 | `<C-/>`        | Show mappings for picker actions (insert mode)       |
 | `?`            | Show mappings for picker actions (normal mode)       |
-| `<C-c>`        | Close telescope                                      |
+| `<C-c>`        | Close telescope (insert mode)                        |
 | `<Esc>`        | Close telescope (in normal mode)                     |
 | `<Tab>`        | Toggle selection and move to next selection          |
 | `<S-Tab>`      | Toggle selection and move to prev selection          |