Add Graduation blog

[fisherxu]

• Please check if the PR fulfills these requirements

• [x] The commit message follows our guidelines

• [ ] Tests for the changes have been added (for bug fixes / features)

• [ ] Docs have been added / updated (for bug fixes / features)

[dingyin]

/lgtm

[kevin-wangzefeng]

/approve

[kubeedge-bot]

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