Consolidate documentation

[juliettelavoie]

I am noticing that there is some duplication between the CMIP7 guidance written here and pages on https://wcrp-cmip.org.

I would suggest consolidating all the information in one place. This would make it easier for people to find the information they need and easier for maintainers to only have one page to edit with new information.

Then, https://wcrp-cmip.org -> CMIP Data -> Documentation could just point to https://wcrp-cmip.github.io/cmip7-guidance/

[juliettelavoie]

@CMIP-IPO thoughts on this ? I wanted to discuss at the WIP also, but we ran out of time.

[eleanororourke]

@juliettelavoie yes, agreed! IPO will implement that