Add back Rocket info to the Onboarding/leads.md

[aryang13]

Add back:

### Rocket Team

Make sure you get added to the `leads` [Rocket](/handbook/tools/slack#rocket) team by the co-presidents. Co-presidents should also make sure they are added to the `exec` Rocket team.

### GitHub Teams

Make sure you are a part of the following teams on GitHub - [Rocket](/handbook/onboarding/everyone.md#rocket-setup) should do this for you if you are a part of the `leads` Rocket team. Check your email for an invitation! Please do not ask to be added directly without checking with `#ask-rocket` if there is a problem.

Put under Google drive:

[Rocket](/handbook/onboarding/everyone.md#rocket-setup) should do this for you - check your email for an invitation! Please do not ask to be added directly without checking with `#ask-rocket` if there is a problem.