docs: Remove experimental disclaimer from README (#695)

README.md

@@ -1,18 +1,6 @@
 [![codecov](https://codecov.io/gh/googleapis/gapic-generator-java/branch/master/graph/badge.svg?token=3RUU37GX9U)](https://codecov.io/gh/googleapis/gapic-generator-java)
 # API Client Generator for Java
 
-A generator for protocol buffer described APIs for and in Java.
-
-This is a generator for API client libraries for APIs specified by protocol
-buffers, such as those inside Google. It takes a protocol buffer (with
-particular annotations) and uses it to generate a client library.
-
-## Purpose
-
-This generator will eventually replace the Java parts of the
+Generates a Java client library from protocol buffers. 
+Replaces the Java parts of the 
 [older monolithic generator](https://github.com/googleapis/gapic-generator).
-
-## Disclaimer
-
-This generator is currently experimental. Please don't use it for anything
-mission-critical.