message: Improve CustomExtension type doc
diff: @@ -3,6 +3,8 @@ import { ExtensionDeclaration } from '../types';
  /**
  * Custom Console extension with arbitrary `type` and `properties`.
  *
  - * This type represents all non-standard Console extension declarations.
  + * This is a special type representing all non-standard Console extension declarations.
  + *
  + * This allows dynamic plugins to consume extensions which are specific to other plugins.
  */
  export type CustomExtension = ExtensionDeclaration<string, { [key: string]: any }>;
  