Add prose documentation for ol.AttributionLike

src/ol/typedefs.js

@@ -43,6 +43,13 @@ ol.AtlasManagerInfo;
 
 
 /**
+ * A type that can be used to provide attribution information for data sources.
+ *
+ * It represents either
+ * * a simple string (e.g. `'© Acme Inc.'`),
+ * * an array of simple strings (e.g. `['© Acme Inc.', '© Bacme Inc.']`),
+ * * an instance of `{@link ol.Attribution}`,
+ * * or an array with multiple `{@link ol.Attribution}` instances.
  * @typedef {string|Array.<string>|ol.Attribution|Array.<ol.Attribution>}
  */
 ol.AttributionLike;