Document repo-specific prompt customization

[neubig]

What problem or use case are you trying to solve?

I believe that OpenHands supports two specific types of repo-specific prompt customization:

1. We have the .openhands_instructions file that is used by the github resolver
2. We have the .openhands directory, which allows for the creation of repo-specific micro-agents.

However, I believe these are not documented in the documentation site.

Describe the UX of the solution you'd like

It would be good to have these documented as a sub-folder under "Prompting" (after "Micro-Agents"):

Do you have thoughts on the technical implementation?

To implement this, it would be good to look through the entire OpenHands directory to references to the ".openhands_instructions" file and ".openhands" directory, understand exactly how they work.

Once we know the mechanisms for these two, they can be documented.

[openhands-agent]

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

[openhands-agent]

A potential fix has been generated and a draft PR #5804 has been created. Please review the changes.

[mamoodi]

One of these is now documented: https://docs.all-hands.dev/modules/usage/prompting/customization

[mamoodi]

From what I've been told the .openhands_instructions is deprecated in favor of the .openhands directory which is documented. Closing.