[Documentation]: Micro-agents

[neubig]

What problem or use case are you trying to solve?

Currently in the openhands/agenthub/codeact_agent directory, we have an implementation of micro agents, but this is not documented.

To do so, we can:

1. read the implementation of codeact agent
2. read an example microagent in openhands/agenthub/codeact_agent/micro/github.md
3. add documentation to openhands/agenthub/codeact_agent/README.md

[github-actions]

OpenHands started fixing the issue! You can monitor the progress here.

[github-actions]

An attempt was made to automatically fix this issue, but it was unsuccessful. A branch named 'openhands-fix-issue-5229' has been created with the attempted changes. You can view the branch here. Manual intervention may be required.