[hotfix][Docs]fix typo and format in state.md & state_v2.md

[Jackeyzhe]

What is the purpose of the change

fix some typo and subtitle format in docs

Brief change log

1、fix 全量快照时进行清理 level in Chinese doc make sure it is same as Cleanup in full snapshot in English doc
2、fix wrong typo for context in state.md and state_v2.md

Verifying this change

only fix doc, it looks good in my local

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (no)
• The serializers: (no)
• The runtime per-record code paths (performance sensitive): (no)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (no)
• The S3 file system connector: (no)

Documentation

• Does this pull request introduce a new feature? (no)

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CI report:

• 637e796 Azure: SUCCESS

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