Rebrand microagents to skills and centralize documentation https://github.com/OpenHands/docs/pull/129

Do we support

.openhands/skills

yet?

In CLI, yes https://github.com/OpenHands/OpenHands-CLI/blob/5e56fabfe7703a70d9816d14b21e055a6ae76808/openhands_cli/tui/settings/store.py#L43