RFR: JDK-8190410 Help.gmk is not updated after consolidation

[Magnus Ihse Bursie]

The help text for "make help" still mentions the old repos.

Also fixed some other minor issues.

Bug: https://bugs.openjdk.java.net/browse/JDK-8190410
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8190410-update-make-help/webrev.01

/Magnus