Revise labels

[frankharkins]

Summary

• Added new labels
  • Visualization
  • Productivity
• Changed / merged existing labels
  • plugin -> Transpiler plugin to closer fits the description in labels.json.
    I've also removed this label from a few projects as I believe they added it thinking it meant "general Qiskit plugin"
  • notebook -> Jupyter notebook
  • Absorbed convert into Converter
  • Absorbed simulation into Physics
• Improved style / readability
  • Expanded acronyms
  • Replaced hypens with spaces
  • Use sentence-style capitalization
• Repo maintenance
  • Replaced references to "tags"
  • Synced label names across issue template, labels.json, and TOML files
  • Reviewed all members to check labels are appropriate

[javabster]

I think we said in the meeting we should keep "circuit simulator" and remove "simulation" correct? And any projects that are in the simulation category should be put into the physics or chemistry

[frankharkins]

@javabster thanks, done!

[frankharkins]

Merging as this was discussed with the team last meeting