Add Abiotic Factor

[RStivanson]

Description

Adds basic support for Abiotic Factor using Proton.

Also added a link to the official game server wiki in the README. It's a repository on (what appears to be) one of the developer's GitHub account, and was advertised in the official steam release announcement.

Note: that the install script downloads the sidecar INI file as the server does not create one by default (just uses the default values if the file doesn't exist). I'm adding the INI alongside such that it is pre-populated in the correct location for the end-user.

Closes pelican-eggs/eggs#2926

Checklist for all submissions

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you tested and reviewed your changes with confidence that everything works?
• Did you branch your changes and PR from that branch and not from your master branch?
  • If not, why?:

New egg Submissions

1. Does your submission pass tests (server is connectable)?
2. Does your egg use a custom docker image?
   • Have you tried to use a generic image?
   • Did you PR the necessary changes to make it work?
3. Have you added the egg to the main README.md and any other README files in subdirectories of the egg (e.g /game_eggs) according to the alphabetical order?
4. Have you added a unique README.md for the egg you are adding according to the alphabetical order?
5. You verify that the start command applied does not use a shell script
   • If some script is needed then it is part of a current yolk or a PR to add one
6. The egg was exported from the panel

[QuintenQVD0]

A port can never be user editable

[RStivanson]

Good catch!

[QuintenQVD0]

Maybe validate here with a between?

[RStivanson]

Added a max of 32.

[QuintenQVD0]

LGTM! Thank you.