<AWT Dev> RFR: JDK-8262420: typo: @implnote in java.desktop module

[Jonathan Gibbons]

Please review some doc changes in `java.awt.TrayIcon`.

Note, the fix is more than the 1-character fix for the typo detected by doclint. The changes are:

1. Fix the name of the `@implNote` tag
2. Remove the redundant `<p>` before the `@implNote` tag
3. Move the `@implNote` tag and its immediate content to after the following paragraph, (beginning _See the ..._) which was originally part of the main description, and does not appear that it should be part of the implementation note.

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

Commit messages:
 - JDK-8262420: typo: @implnote in java.desktop module

Changes: https://git.openjdk.java.net/jdk/pull/2735/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2735&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262420
  Stats: 7 lines in 1 file changed: 2 ins; 3 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2735.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2735/head:pull/2735

PR: https://git.openjdk.java.net/jdk/pull/2735