Add email templates

[esaumell]

Would be really helpful to add email templates to copy-paste for each of the email call to actions:

It will be a LOT easier for people to act

[esaumell]

I can help to translate from English to Catalan, German and Spanish

[candideu]

Came here to say just this! Here's a doc to start working on some text:

https://pad.disroot.org/p/Keep_Android_Open