[lworld] Integrated: 8244232: [lworld] Improve javadoc comments for various methods dealing with projection types

[Srikanth Adayapalam]

Update javadoc to reflect differences between referenceProjection APIs and the ref operator of the spec.

-------------

Commit messages:
 - 8244232: Improve javadoc comments for various methods dealing with projection types

Changes: https://git.openjdk.java.net/valhalla/pull/148/files
 Webrev: https://webrevs.openjdk.java.net/valhalla/148/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8244232
  Stats: 21 lines in 2 files changed: 18 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/148.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/148/head:pull/148

PR: https://git.openjdk.java.net/valhalla/pull/148