Delete documentation that is now covered by GCP docs

[rramkumar1]

Ref: #557

The bulk of the deletions here are happening in examples/ and in docs/annotations.md. All of this is now moved over to the GCP docs (see README.md for the links).

Also note that the new README.md mentions that CHANGELOG.md will contain high-level release notes along with a list of all changes. The high-level release notes will come in another CL.

[rramkumar1]

/assign @steveperry-53
/assign @MrHohn
/assign @freehan
/assign @agau4779
/assign @bowei

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/assign @steveperry-53
/assign @MrHohn
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[steveperry-53]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rramkumar1, steveperry-53

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[rramkumar1]

/hold
So more people can take a look and LGTM

[rramkumar1]

Oops, looks like I added the hold label too late. Can make changes in a followup if there are any comments.