Add org level README

[nickynicolson]

It would be helpful to have a organisational level README which orients new (and existing!) users around the different projects housed under this CoL organisation.
Github guidelines on organisational profiles here: https://docs.github.com/en/organizations/collaborating-with-groups-in-organizations/customizing-your-organizations-profile

[mdoering]

very much agree!
We should at least mention:

• API
• CLB UI
• COL portal
• portal components
• coldp
• data feedback repo
• the many data-* coldp repo

I also had many people using gbif/checklistbank when they were looking for the col one. The note there that points here might need to be more prominent.

[mjy]

Thinking links or references to

• Licenses
• Citation
• Contributing
• Code of conduct

[nickynicolson]

Thinking links or references to

• Licenses
• Citation
• Contributing
• Code of conduct

These are more likely repo level entries, but a statement of intent that each repo in the org has them would be nice