Refactor: Development & Plugins & About sections in the Docs

[arm4b]

Some refactoring notes:

• About section in the docs includes Contributing Guide and Development Guide. This should be moved to the Development section.
• Development section includes scattered incomplete guides to create a custom plugins Docker image, duplicating the existing Plugins docs. This should be moved to the Plugins.
• Another idea to explore is removing the About section as it's not that informative. Maybe renaming to Community? (DCO, License, Code of Conduct, Meetings, Github Issues, Discussions).