Update readme to mention dbstat

Author: simolus3

README.markdown

@@ -35,7 +35,7 @@ To use SQLite in your project, add `pod 'sqlite3'` to your Podfile. However, as
 - [Spellfix1](https://www.sqlite.org/spellfix1.html): `pod 'sqlite3/spellfix1'`
 - [STAT4 Enhanced ANALYZE and query planner](https://sqlite.org/compile.html#enable_stat4): `pod 'sqlite3/stat4'`
 - [Unlock-Notify API](https://www.sqlite.org/unlock_notify.html): `pod 'sqlite3/unlock_notify'`
-
+- [DBSTAT](https://www.sqlite.org/dbstat.html): `pod 'sqlite3/dbstatvtab'`
 
 ## License