Added Xonsh is a python-powered, cross-platform, unix-gazing shell language and command prompt.

[anki-code]

What kind of change does this PR introduce?

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

Description:

Xonsh is a Python-powered, cross-platform, Unix-gazing shell language and command prompt. The language is a superset of Python 3.6+ with additional shell primitives that you are used to from Bash and IPython. It works on all major systems including Linux, OSX, and Windows. Xonsh is meant for the daily use of experts and novices.

Checklist:

• [x] I have read the CONTRIBUTING guidelines.
• [x] 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.