Add mention of inner class access syntax in Java interop section

[jafingerhut]

perhaps with a link to this article:

http://blog.jayfields.com/2011/01/clojure-using-java-inner-classes.html

[jafingerhut]

I added $ to Special Characters section in the last few months, but did not add a link to the article mentioned in the previous comment. That still looks like a good idea.