RFR: 8343609: Broken links in java.xml

[Joe Wang]

Fix broken links in java.xml:

Catalog: contacted Oasis. The standard page (https://www.oasis-open.org/standard/xmlcatalogs/) now links to the PDF version. That is what I'm using now, replacing the html pages. Not ideal, but at least it's displayed within the browser rather than downloaded as the html version did.

QName: rewrote the javadocs.

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Commit messages:
 - 8343609: Broken links in java.xml

Changes: https://git.openjdk.org/jdk/pull/23242/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23242&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343609
  Stats: 78 lines in 7 files changed: 2 ins; 38 del; 38 mod
  Patch: https://git.openjdk.org/jdk/pull/23242.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23242/head:pull/23242

PR: https://git.openjdk.org/jdk/pull/23242