Fix Help button URL

Summary

Summarize the bug encountered concisely. The help button goes to Mozilla's help page, it should go to ours

Steps to reproduce:

How one can reproduce the issue - this is very important.

1. Connect to Tor
2. Tap on the kebab menu
3. Tap on "Help"
4. Notice the page we go to is Mozilla's help page

What is the current bug behavior?

It opens Mozilla's help page

What is the expected behavior?

It should go to our help page

Environment

Which operating system are you using? For example: Debian GNU/Linux 10.1, Windows 10, Ubuntu Xenial, FreeBSD 12.2, etc. Which installation method did you use? Distribution package (apt, pkg, homebrew), from source tarball, from Git, etc.

Relevant logs and/or screenshots