[ashwin31]

What kind of change does this PR introduce?

• Add a project
• Update a project
• Remove a project
• Add or update a category
• Change configuration
• Documentation
• Other, please describe:

Description:

Adds mkdocs-onlinecompiler, a MkDocs plugin that makes code blocks runnable: write runnable after a code block's language (```python runnable) and readers get an editor with a Run button in the page. The code runs in a sandbox on OnlineCompiler.io, in 46 languages, and it works with Material for MkDocs (admonitions, content tabs, snippets, instant navigation).

• PyPI: https://pypi.org/project/mkdocs-onlinecompiler/ (0.1.0, MIT)
• GitHub: https://github.com/onlinecompiler-io/mkdocs-onlinecompiler
• Entry point: onlinecompiler (mkdocs.plugins)
• Category: code-exec-templating, next to markdown-exec and mkdocs-jupyter

Checklist:

• I have read the CONTRIBUTING guidelines.
• I have not modified the README.md file. Projects are only supposed to be added or updated within the projects.yaml file since the README.md file is automatically generated.