Documented external caching API inline

mustache.mjs

@@ -669,9 +669,17 @@ var mustache = {
   Scanner: undefined,
   Context: undefined,
   Writer: undefined,
+  /**
+   * Allows a user to override the default caching strategy, by providing an
+   * object with set, get and clear methods. This can also be used to disable
+   * the cache by setting it to the literal `undefined`.
+   */
   set templateCache (cache) {
     defaultWriter.templateCache = cache;
   },
+  /**
+   * Gets the default or overridden caching object from the default writer.
+   */
   get templateCache () {
     return defaultWriter.templateCache;
   }