[jfx15] RFR: 8246343: Fix mistakes in FX API docs [v3]

[Nir Lisker]

> Fixes https://bugs.openjdk.java.net/browse/JDK-8246343 and some additional fixes in the vicinity.

Nir Lisker has updated the pull request incrementally with one additional commit since the last revision:

  VBox and HBox fixes

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

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/274/files
  - new: https://git.openjdk.java.net/jfx/pull/274/files/5c7d74ef..141e78f1

Webrevs:
 - full: https://webrevs.openjdk.java.net/jfx/274/webrev.02
 - incr: https://webrevs.openjdk.java.net/jfx/274/webrev.01-02

  Stats: 11 lines in 2 files changed: 0 ins; 2 del; 9 mod
  Patch: https://git.openjdk.java.net/jfx/pull/274.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/274/head:pull/274

PR: https://git.openjdk.java.net/jfx/pull/274