[meta] Allow editing of GitHub Wiki or enable it

[Mikaela]

As https://github.com/SijmenSchoon/telematrix/wiki goes to https://github.com/SijmenSchoon/telematrix/ I think it's disabled in repostiory settings.

I would like to write documentation there on at least:

• public instances (Telegram bot | homeserver | client (riot) | comment)
• End-user howto

---

0. Create a group at Telegram if one doesn't already exist.
1. Add the bot to the group at Telegram.
2. Say /alias at the group
3. Move to Matrix
   1. Create a room if one doesn't already exist.
   2. Copy-paste the alias to room address in Matrix room settings.
4. Ensure that the room can be joined by anyone who knows the address (guests don't matter)

[vijfhoek]

I've enabled it. I'll just keep this open for now because of the to be created documentation.