Update README.md

Author: rafamizes

README.md

@@ -23,6 +23,8 @@ Rultor.com](https://www.rultor.com/b/dartoos-dev/json_cache)](https://www.rultor
 - [Getting Started](#getting-started)
 - [List of JsonCache implementations](#list-of-jsoncache-implementations)
   - [JsonCacheMem — Thread-safe In-memory cache](#jsoncachemem)
+    - [Typical Usage](#typicalusage)
+    - [Cache Initialization](#cacheinitializationconstructor) 
   - [JsonCachePrefs — SharedPreferences](#jsoncacheprefs)
   - [JsonCacheLocalStorage — LocalStorage](#jsoncachelocalstorage)
   - [JsonCacheCrossLocalStorage — CrossLocalStorage](#jsoncachecrosslocalstorage)
@@ -152,7 +154,7 @@ object. For example:
     await jsonCache.remove(userId);
   }
 ```
-#### JsonCacheMem.init
+#### Cache Initialization Constructor
 
 [JsonCacheMem.init](https://pub.dev/documentation/json_cache/latest/json_cache/JsonCacheMem/JsonCacheMem.init.html)
 is the constructor whose purpose is to initialize the cache upon object