Change website domain of NewPipe in readmes

[AudricV]

What is it?

• Bugfix (user facing)
• Feature (user facing)
• Codebase improvement (dev facing)
• Meta improvement to the project (dev facing)

Description of the changes in your PR

This PR changes NewPipe's website domain to the new domain in readmes.

Fixes the following issue(s)

#5109

Due diligence

• I read the contribution guidelines.

[triallax]

There is still one place in the NewPipe codebase where newpipe.schabi.org is still used:

NewPipe/app/src/main/java/org/schabi/newpipe/report/ErrorActivity.java

Line 79 in 8bcf0c6

public static final String ERROR_EMAIL_ADDRESS = "crashreport@newpipe.schabi.org";

However, I'm not sure if changing it to newpipe.net is fine, so I'll ask whoever's in charge of infrastructure.

Edit: I asked about this, and apparently the e-mail address is still not changed, so we'll have to stick with crashreport@newpipe.schabi.org for now.

[TobiGr]

Thank you

[TobiGr]

We did not change the email address yet.