Role Strategy Plugin 2.14

Maintenance release (publishing GitHub documentation in the plugin site, test automation for Java 11, etc.). There is no user-facing or bugfixes included in this release.

📝 Documentation updates

• JENKINS-59172 - Use GitHub as a source of the plugin's documentation on plugins.jenkins.io (#103) @oleg-nenashev

📦 Dependency updates

• Bump configuration-as-code from 1.21 to 1.29 (#96, #100, #101, #102) @dependabot

🚦 Internal changes

• Cleanup whitespaces in the code (#99) @karnauskas
• Enable Dependabot to keep development tools up to date (#97) @oleg-nenashev
• Delete the obsolete CONTRIBUTORS file (#95) @oleg-nenashev
• Enable Java 11 tests in the pull request builder (#96) @oleg-nenashev