docs: polish from-kubernetes documents and kubernetes overview documents

[Peefy]

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

• N
• Y

docs: polish from-kubernetes documents and kubernetes overview documents

2. What is the scope of this PR (e.g. component or file name):

• docs/user_docs/guides/working-with-k8s/0-overview.md
• docs/user_docs/guides/working-with-k8s/1-adopt-from-kubernetes.md
• docs/user_docs/guides/working-with-k8s/2-generate-k8s-manifests.md
• examples/kubernetes/**

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Other

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

• N
• Y

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

• Unit test
• Integration test
• Benchmark (add benchmark stats below)
• Manual test (add detailed scripts or steps below)
• Other

• examples/kubernetes/**