RFR: 8378366: Accessibility issues in CSS Reference Guide and Introduction to FXML [v3]

[Andy Goryachev]

> Addressing the accessibility issues in JavaFX CSS Reference Guide and Introduction to FXML documents:
> 
> [JDK-8378306](https://bugs.openjdk.org/browse/JDK-8378306) In JavaFX CSS Reference Guide, a `<ul>` element must appear within an `<li>` element
> [JDK-8378308](https://bugs.openjdk.org/browse/JDK-8378308) In JavaFX CSS Reference Guide, <textarea> elements do not contain a label
> [JDK-8378309](https://bugs.openjdk.org/browse/JDK-8378309) In JavaFX CSS Reference Guide and Introduction to FXML, there are color contrast issues
> [JDK-8378310](https://bugs.openjdk.org/browse/JDK-8378310) In JavaFX CSS Reference Guide and Introduction to FXML, a "Skip to Main Content" link doesn't exist
> [JDK-8378307](https://bugs.openjdk.org/browse/JDK-8378307) In JavaFX CSS Reference Guide, some tables don't use the scope attribute or the <caption> element
> 
> For ease of reviewing, the first 5 commits correspond to individual tickets.
> 
> Most of the changes are trivial, but for [JDK-8378307](https://bugs.openjdk.org/browse/JDK-8378307) I decided to replace the table with `<ul>` list used elsewhere in similar situations.
> 
> In [JDK-8378308](https://bugs.openjdk.org/browse/JDK-8378308) the `<textarea>`s were made read-only because obviously.

Andy Goryachev has updated the pull request incrementally with one additional commit since the last revision:

  tabs

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/2082/files
  - new: https://git.openjdk.org/jfx/pull/2082/files/f58ee41d..78bac1dd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=2082&range=02
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=2082&range=01-02

  Stats: 10 lines in 2 files changed: 0 ins; 0 del; 10 mod
  Patch: https://git.openjdk.org/jfx/pull/2082.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/2082/head:pull/2082

PR: https://git.openjdk.org/jfx/pull/2082