Add categories to Github discussions

[tpecar]

Add additional categories which would be useful to the project

• Troubleshooting - for helping people setting up their board
• Documentation - for discussion about tutorials, learning materials, Wiki
• Development - for research on the development board, promotion of useful tools and projects

I would use the "Open ended discussion" format for these.

Existing categories are very general, but I would keep them for whatever discussion that doesn't fit in the suggested categories.

[tpecar]

Thank you for creating the categories.