Documentation for older versions

[costinm]

The doc seems to match the latest version - I found no link to the older versions, nor indication in the doc on when each keyword was added, and info about keywords that existed in prior versions and was removed.

Some tools are bundled with old version - like 1.7. At least v1 doc should be maintained and accessible.

[briandealwis]

In the meantime, you can check out the corresponding release and run make preview-docs to view the docs locally.

[aaron-prindle]

Currently we have v1 docs at:
https://skaffold-v1.web.app/

v2 (@Head) docs at:
skaffold.dev

and we have documents related to every schema version at:
https://skaffold.dev/docs/references/yaml/?version=v3