Improve documentation on how to get started with CAst Java source front end

[EdisonE3]

Hello! Recently, I want to use CAst to do some analysis because compiling whole Java project cost a lot of time. Are there some Demo of using CAst to read and analysis Java project?

[msridhar]

Sorry the docs are bad here. The SourceDirCallGraph is a example driver showing how to use the Java source front end:

https://github.com/wala/WALA/blob/master/com.ibm.wala.cast.java.ecj/src/main/java/com/ibm/wala/cast/java/ecj/util/SourceDirCallGraph.java

I'll leave this issue open to improve the docs around this.