[Copilot]

No documentation existed for using setup-java with JavaFX Maven projects, despite the feature being supported via java-package: jdk+fx.

Changes:

• Added ### JavaFX Maven project subsection under ## Installing custom Java package type in docs/advanced-usage.md
  • Explains use of java-package: jdk+fx (or jre+fx) with supported distributions (zulu, liberica)
  • References the openjfx.io Getting Started guide for pom.xml setup
  • Includes workflow snippets for mvn compile and mvn javafx:run
• Updated table of contents to include the new subsection

Example workflow snippet:

- uses: actions/setup-java@v5
  with:
    distribution: 'zulu'
    java-version: '21'
    java-package: jdk+fx
    cache: maven
- name: Build with Maven
  run: mvn --no-transfer-progress compile

Related issue:
Closes #568

Check list:

• Mark if documentation changes are required.
• Mark if tests were added or updated to cover the changes.