[Doc] Documentation Needed for eventmesh-connector-spring

### Search before asking

- [X] I had searched in the [issues](https://github.com/apache/eventmesh/issues?q=is%3Aissue) and found no similar issues.

### Documentation Related

Currently, most connectors lack documentation. The following details must be added to provide better clarity to the developers:- 1. functions of the current connector
2. descriptions of configuration items
3. precautions (if any),
4. relevant official reference links (if any),
5. Other specific content that needs to be explained in the documentation.
Having these details can increase the clarity for the users who are using the product and can also help in onboarding the new developers easily

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct) *

Start by locating the eventmesh-connector-spring connector and any existing documentation or configuration references. Document the connector's functions, configuration items, precautions, official references, and other relevant usage details, then confirm the resulting documentation is complete and understandable for users and new developers.

Written by the indexing model from the issue text.