Unfortunately we have published API Reference for Framework for the last version of RichFaces only.
If you want to see API docs for Framework 3.1.4 you should:
1. checkout 3.1.4 version from SVN: http://anonsvn.jboss.org/repos/richfaces/tags/3.1.4.GA/ (for example, in 'RF' folder:)
2. rebuild from the root of the 'RF' folder
3. cd to framework dir
4. use javadoc tool or if you use maven run: mvn javadoc:javadoc