Add Modern Mermaid plugin to community plugins list

[wis-graph]

Add new plugin for rendering latest Mermaid diagrams with support for light/dark themes and clipboard copy functionality.

[github-actions]

Hello!

I found the following issues in your plugin submission

Errors:

❌ You did not follow the pull request template. The PR template can be found here
❌ Please don't use the word obsidian in the plugin ID. The ID is used for your plugin's folder so keeping it short and simple avoids clutter and helps with sorting.
❌ Please don't include Obsidian in the plugin description
❌ Your description needs to have one of the following characters at the end: .?!)
❌ Plugin ID mismatch, the ID in this PR (obsidian-modern-mermaid) is not the same as the one in your repo (newmermaid). If you just changed your plugin ID, remember to change it in the manifest.json in your repo and your latest GitHub release.
❌ Plugin name mismatch, the name in this PR (Modern Mermaid) is not the same as the one in your repo (New Mermaid). If you just changed your plugin name, remember to change it in the manifest.json in your repo and your latest GitHub release.
❌ Description mismatch, the description in this PR (Render latest Mermaid diagrams in Obsidian) is not the same as the one in your repo (Render latest Mermaid diagrams). If you just changed it, remember to change it in the manifest.json in your repo and your latest GitHub release.
❌ Unable to find a release with the tag 1.0.0. Make sure that the version in your manifest.json file in your repo points to the correct Github Release.
❌ Your repository does not include a license. Go to https://choosealicense.com/ to compare different open source licenses.

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