Update documentation to refer to other projects that use CMOR

[mauzey1]

We probably need to start pulling out the direct references to the CMIP6 project, and rather start listing projects using CMOR. CMIP6 is effectively closed for registrations, with new models/experiments being defined in CMIP6Plus_CVs for now, and CMIP7_CVs online in the coming months. Then there is input4MIPs and obs4MIPs, amongst other projects (DRCDP, etc) using the software

Originally posted by @durack1 in #146 (review)

[durack1]

I note that many of the CMOR-wrappers that I have been able to identify are included in the table D1 in Durack et al., 2025, in review