Improve the CN document description

[daviderli614]

• https://docs.greptime.cn/user-guide/concepts/why-greptimedb#%E5%B0%8F%E7%BB%93
  The version of GreptimeDB describe in the document is too old
  

• https://docs.greptime.cn/user-guide/concepts/architecture
  Maybe is datanode ？

• https://docs.greptime.cn/user-guide/concepts/key-concepts
  Is the font style correct?
  

• https://docs.greptime.cn/user-guide/ingest-data/for-observerbility/vector#%E9%9B%86%E6%88%90
  type=greptimedb is old version, reference: https://vector.dev/docs/reference/configuration/sinks/greptimedb_metrics/
  Can be changed to greptimedb_metrics.

• https://docs.greptime.cn/user-guide/ingest-data/for-iot/grpc-sdks/go#%E5%AE%89%E8%A3%85
  The SDK version too old.
  

• https://docs.greptime.cn/user-guide/administration/upgrade
  The version too old.

[nicecui]

Thank you for your feedback.

1. The following content has been updated:

• Why GreptimeDB
• typos
• SDK version

2. The example versions in the upgrade documentation is exactly the corresponding versions. If the example steps have not changed, we can keep it.
3. The Vector configuration issue is moved to fix the configurations of Vector #1407