Add Yoself to service monitoring alternatives (#1618)

### Description of Changes

Another tool of mine, used for monitoring production containers and website servers for two months. Can also be used as a partial alternative to Uptime Kuma, but listing it below because the overlap is small. Copied [contributing agreement](https://codeberg.org/nykula/yoself/src/branch/main/CONTRIBUTING.md) from EviKit, for which it's is one of the demos.

- [x] no previous strikes or bans in the repo
- [x] project is completely FOSS
- [x] project has a "Code of Conduct"
- [x] project has a "No AI Policy"

Reviewed-on: https://codeberg.org/ethical-foss/open-slopware/pulls/1618
Reviewed-by: Ethical FOSS admin <ethical-foss-admin@noreply.codeberg.org>

README.md

@@ -2500,6 +2500,7 @@ Here, "RSS Aggregators" means services which run on a server (often self-hosted)
 > ### Service Monitoring Alternatives
 > * [GoatCounter](https://github.com/arp242/goatcounter) [![Anti-AI Policy](./badges/anti-ai-policy.svg)](#anti-ai-policy) ([1](https://github.com/arp242/goatcounter/blob/main/CONTRIBUTING.md#ai-policy)) - privacy-friendly web analytics
 > * [Healthchecks](https://github.com/healthchecks/healthchecks) [![Anti-AI Policy](./badges/anti-ai-policy.svg)](#anti-ai-policy) ([1](https://github.com/healthchecks/healthchecks/blob/master/CONTRIBUTING.md#ai-policy)) - cron job and background task monitoring
+> * [Yoself](https://codeberg.org/nykula/yoself) [![Anti-AI Policy](./badges/anti-ai-policy.svg)](#anti-ai-policy) ([1](https://codeberg.org/nykula/yoself/src/branch/main/CONTRIBUTING.md)) - status page for Docker/Podman and website availability
 
 ## Social Media