RFR [9] 8080880: some docs cleanup for langtools

[alexander stepanov]

Hello,

Could you please review the following fix
http://cr.openjdk.java.net/~avstepan/8080880/webrev.00/
for
https://bugs.openjdk.java.net/browse/JDK-8080880
Just some minor fix for docs, no other code touched.

The affected packages should (probably) not be visible in the new 
modular system, but nevertheless...

Thanks,
Alexander