update docs

docs/realm.js

@@ -107,9 +107,11 @@ class Realm {
  * Get the current schema version of the Realm at the given path.
  * @param {string} path - The path to the file where the
  *   Realm database is stored.
+ * @param {string} encryptionKey - Optional encryption key.
+ * @throws {Error} When passing an invalid or non-matching encryption key.
  * @returns {number} version of the schema, or `-1` if no Realm exists at `path`.
  */
-Realm.schemaVersion = function(path) {};
+Realm.schemaVersion = function(path, encryptionKey) {};
 
 /**
  * The default path where to create and access the Realm file.