docs(config): add logLevel to config options (#3998)

Author: brandyscarney

docs/developing/config.md

@@ -178,6 +178,7 @@ Below are the config options that Ionic uses.
 | `loadingEnter`              | `AnimationBuilder`                                                                | Provides a custom enter animation for all `ion-loading`, overriding the default "animation".                                                                                                                                                                                           |
 | `loadingLeave`              | `AnimationBuilder`                                                                | Provides a custom leave animation for all `ion-loading`, overriding the default "animation".                                                                                                                                                                                           |
 | `loadingSpinner`            | `SpinnerTypes`                                                                    | Overrides the default spinner for all `ion-loading` overlays.                                                                                                                                                                                                                          |
+| `logLevel`                  | `'OFF' \| 'ERROR' \| 'WARN'`                                                      | Configures the logging level for Ionic Framework. If `'OFF'`, no errors or warnings are logged. If `'ERROR'`, only errors are logged. If `'WARN'`, errors and warnings are logged.                                                                                                     |
 | `menuIcon`                  | `string`                                                                          | Overrides the default icon in all `<ion-menu-button>` components.                                                                                                                                                                                                                      |
 | `menuType`                  | `string`                                                                          | Overrides the default menu type for all `<ion-menu>` components.                                                                                                                                                                                                                       |
 | `modalEnter`                | `AnimationBuilder`                                                                | Provides a custom enter animation for all `ion-modal`, overriding the default "animation".                                                                                                                                                                                             |