Update onboarding and post-graduation checklists to match new CoC policy

[tobie]

The new CoC policy (which is yet to be merged) is more explicit in what it requires from projects that want to manage CoC reports themselves.

Let's make sure that the onboarding and post-graduation checklists match those requirements.

Once the checklists are updated, we should reach out to projects which might need to be updated:

• AMP Project
• Appium
• Electron
• Express.js
• Fastify
• HospitalRun
• LoopBack
• Node.js
• Node-RED
• Webdriver.io
• Webhint

[tobie]

Closely related to #1251.

[tobie]

As discussed in the CPC meeting today, lets focus on the first phase for now which is to update the checklists.