chore(README): fix typo

Author: doshprompt

README.md

@@ -29,7 +29,7 @@ ___
     - [i18n directive](#i18n-directive)
         - [Localize Using the i18n attribute](#localize-using-the-i18n-attribute)
         - [Localize with Dynamic User Data](#localize-with-dynamic-user-data)
-    - [i18nAttr directive](#i18nAttr-directive)
+    - [i18nAttr directive](#i18nattr-directive)
     - [locale service](#locale-service)
     - [i18n filter](#i18n-filter)
     - [Sample App](#sample-app)