doc: cut v1.21.7 release

[andyzhangx]

What type of PR is this?
/kind feature

What this PR does / why we need it:
doc: cut v1.21.7 release

Which issue(s) this PR fixes:

Fixes #

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Special notes for your reviewer:

git checkout -b cut-v1.21.7
sed -i 's/v1.21.6/v1.21.7/g' Makefile
sed -i 's/v1.21.6/v1.21.7/g' README.md
git diff
cd charts/
sed -i 's/v1.21.6/v1.21.7/g' README.md
sed -i 's/: v1.21.6/: v1.21.7/g' latest/blob-csi-driver/values.yaml
sed -i 's/: v1.21.6/: v1.21.7/g' latest/blob-csi-driver/Chart.yaml
cd latest
helm package blob-csi-driver
git rm blob-csi-driver-v1.21.6.tgz
git add blob-csi-driver-v1.21.7.tgz
cd ..
cp latest/ v1.21.7 -r
cd v1.21.7/
helm package blob-csi-driver
rm blob-csi-driver-v0.0.0.tgz
git add blob-csi-driver-v1.21.7.tgz
cd ../../
helm repo index charts --url=https://raw.githubusercontent.com/kubernetes-sigs/blob-csi-driver/master/charts
sed -i 's/v1.21.6/v1.21.7/g' deploy/blobfuse-proxy/README.md
cd ./deploy/
sed -i 's/:v1.21.6/:v1.21.7/g' *.yaml
mkdir v1.21.7
cp *.yaml v1.21.7/
cd ../docs/
cp install-csi-driver-master.md install-csi-driver-v1.21.7.md
grep master install-csi-driver-v1.21.7.md
sed -i 's/master/v1.21.7/g' install-csi-driver-v1.21.7.md
cd ..
sed -i 's/v1.21.6/v1.21.7/g' docs/install-blob-csi-driver.md
#vi docs/install-blob-csi-driver.md
git add charts/ deploy/ docs
$git_commit
git push origin cut-v1.21.7

Release note:

none

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andyzhangx

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[andyzhangx]

/retest

[k8s-ci-robot]

@andyzhangx: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-blob-csi-driver-external-e2e-nfs	1e00aec	link	true	/test pull-blob-csi-driver-external-e2e-nfs

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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