feat(repo): remove default manga repo

[Secozzi]

If the support channel in discord is anything to go by, having this repo added as default just leads to people who don't know anything about self-hosting attempting to use these extensions, which they shouldn't. Besides, the extensions in the repo are being updated maintained elsewhere so even if you are using these extensions, using them from this repo doesn't make much sense

[hollowshiroyuki]

now do it with the anime repo 🔫