R1:7157dd96b34a

T15006: Update .arcconfig to point to we.phorge.it

Summary:
Update the `.arcconfig` file to point to our decided-upon URL for hosting

Refs T15006

Test Plan:
I used `arc which` and verified it identified `https://we.phorge.it`:
```lang=console
REPOSITORY
To identify the repository associated with this working copy, arc followed this process:

Configuration value "repository.callsign" is empty.

This repository has no VCS UUID (this is normal for git/hg).

The remote URI for this working copy…