Update README.md (#116)

Due to there being several third-party SDKs in different languages of varying quality / age, adding "official" to the phrasing of the title should help people understand that this is owned and maintained by Optimizely.

Author: zleach

README.md

@@ -3,7 +3,7 @@
 </h3>
 
 <p align="center">
-  This repository houses the JavaScript SDK for use with Optimizely X Full Stack
+  This repository houses the official JavaScript SDK for use with Optimizely X Full Stack
 </p>
 
 ## Packages
@@ -21,4 +21,4 @@ This repository is a monorepo that we manage using [Lerna](https://github.com/le
 
 ### Contributing
 
-Please see [CONTRIBUTING](CONTRIBUTING.md).
+Please see [CONTRIBUTING](CONTRIBUTING.md).