RFR: 8199902: {@docRoot} references need to be updated to reflect new module/package structure

[Jonathan Gibbons]

Please review some simple fixes to update {@docRoot} references in 
documentation comments, in accordance with the new documentation 
organization.

JBS: https://bugs.openjdk.java.net/browse/JDK-8199902
Webrev: http://cr.openjdk.java.net/~jjg/8199902/webrev.00/
-- Jon