Changelog for 1.0 RC1 release

[ddebroy]

Note that Disk, Volume, FS and SMB API groups will be moving up to v1 as part of the v1 RC 1 -> v1 transition.

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/kind api-change
/kind bug
/kind cleanup
/kind design

/kind documentation

/kind failing-test
/kind feature
/kind flake

What this PR does / why we need it:
Changelog for 1.0 RC1 release

Does this PR introduce a user-facing change?:
No

NONE

[k8s-ci-robot]

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[jingxu97]

/assign @mauriciopoppe
lgtm, @mauriciopoppe could you give a final review?

[mauriciopoppe]

There were a few changes in the message fields too, the one that's important was changing disk_id (string) to disk_number (uint32) in Volume and Disk, these change are summarized in the github issues attached to each PR.

I think we could add something like:

The complete list of changes is summarized in #[issue number]

[mauriciopoppe]

@jingxu97 suggested adding more changes in a document that has more details on how to upgrade, I think that's a good approach too

/lgtm