* Update v2 docs links to new subdomain

* Update README.md

remove line mentioning v6 since that's out of support

Co-authored-by: Shwetha Gururaj <shwetha.gururaj@broadcom.com>

* Revert most of 281d2744ccd2546ed8c4364ef230691c867a606c

after discussion on [#3029](https://github.com/cloudfoundry/cli/pull/3029

) since the original routes will point at the v3 API docs,
which link to v2 docs and are therefore more applicable for commands such as curl that depend on either/both

thanks @gururajsh

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Co-authored-by: Shwetha Gururaj <shwetha.gururaj@broadcom.com>