Create a page with Community Plugins

Currently, high-quality plugins developed by the community (e.g., specialized sensors, specific actuator controllers, or visual effects) are scattered across individual GitHub repositories. New users often struggle to find these resources, leading to "reinventing the wheel" or missing out on powerful tools that aren't part of the core gz-sim library.

I would like to see a dedicated "Community Plugins" page—either within the official documentation (gazebosim.org) or as a curated list in the repository—to showcase these contributions.

# Alternatives considered
Searching GitHub/Bitbucket: Users currently rely on manual searches or "Awesome Gazebo" lists, which can become outdated or hard to find.

Third-party Wikis: Community-run wikis exist but often lack the authority and visibility of the official Gazebo documentation.

# Implementation suggestion
Documentation Integration: Add a "Community Plugins" section to the [Gazebo Sim Documentation](https://gazebosim.org/docs).

Categorization: Organize plugins by type (e.g., Sensors, Physics/System, GUI, Rendering).

Submission Process: Use a simple YAML-based registry or a specific "community-plugin" GitHub label that triggers an automated update to the list, or simply a curated Markdown file in a community folder.

Metadata: Each entry should include:

Plugin Name

Supported Gazebo versions (e.g., Harmonic, Ionic)

Brief description

Link to the repository

Start by reviewing the Gazebo Sim Documentation at gazebosim.org/docs and the repository's existing documentation structure. Compare the proposed curated Markdown file or YAML-based registry, then define categories and entries containing the plugin name, supported Gazebo versions, description, and repository link. Done means the Community Plugins page is published and its submission or maintenance process is documented.

Written by the indexing model from the issue text.