Document supported Netbox versions

[jrbeilke]

Have been using this with Netbox v2.8 to successfully sync and manage a number of resources from AWS and other providers, but looking to upgrade to v2.10 and it seems that support is lacking for certain features.

Would be nice if the README noted which Netbox versions and/or features were supported, and by which version of python-netbox.

In particular v2.10 introduced support for bulk updates/deletes to the Netbox API, and a new implementation of custom fields which seems to be missing from python-netbox:
https://netbox.readthedocs.io/en/stable/release-notes/version-2.10/

[jagter]

Thanks for this good suggestion!

My idea right now is to match the python-netbox versions with the netbox versions for compatibility.