Add link to DevSeed's Cloud Optimized Geospatial Formats Guide

[j08lue]

Acceptance criteria

• [ ] Added link to ~https://developmentseed.org/cloud-optimized-geospatial-formats-guide/~ https://guide.cloudnativegeo.org/ in a suitable location

[jsignell]

I'm getting a 404. Did this maybe move to https://guide.cloudnativegeo.org/ ?

[wildintellect]

@jsignell try again, it's github pages hosted afaik. Oh yes the original url changed.