[fix] remove Gitpod setup info from all repos

[thegrumpyenby]

Since we’re not using Gitpod anymore, we should remove references to it in all repo READMEs:

• next website readme: https://github.com/distributeaid/next-website-v2/blob/saga/README.md#-getting-started-with-gitpod
• needs assessment readme: https://github.com/distributeaid/needs-assessment-v2/blob/main/README.md#-getting-started-with-gitpod
• api readme: https://github.com/distributeaid/aggregated-public-information/blob/saga/README.md#gitpod-development-%EF%B8%8F
• docs gitpod setup (whole file essentially moot): https://github.com/distributeaid/docs/blob/saga/how-to-DA/gitpod-setup.md