docs: Added some info on harbor and artipie

caching.md

@@ -113,11 +113,27 @@ License evaluation needed
 
 #### Artipie
 
+[GH](https://github.com/artipie/artipie)
+[Wiki](https://github.com/artipie/artipie/wiki)
+
+- MIT License
+
 - might be abandoned / low dev activity / needs new maintainer
   - However, technically it looks extremely promising
+  - Initial setup does not run out of the box correctly, needs some love
+- Mostly headless
+  - Brings a limited web interface
+    - Repo creation, artifact viewing
+
+- Pro: Config in yaml file
 
 #### Pulp
 
+[Website](https://pulpproject.org/)
+[GH](https://github.com/pulp/pulpcore)
+
+- GPL 2.0 License
+
 - Pull-Through Caches are only technical previews and might not work correctly
 
 #### kube-image-keeper
@@ -139,10 +155,30 @@ License evaluation needed
 
 #### 'Simple' Squid proxy (or similar)
 
-- Caching of arbitrary resouces via HTTP
+- Caching of arbitrary resources via HTTP
+- "Stupid" caching
+  - Invalidation becomes a problem rather quickly
 
 #### Harbor
 
+[Website](https://goharbor.io/)
+[GH](https://github.com/goharbor/harbor)
+
+- Apache 2.0 License
+
+- The go-to container registry
+- Allows self-hosting artifacts and caching upstream ones
+
+- Pro: Image Signing
+- Pro: Multi Tenant
+- Pro: Quotas
+- Pro: Vulnerability Scans
+- Pro: SBOM creation
+- Pro: P2P distribution of artifacts
+- Pro: fully fledged web interface
+
+- Con: Only Container / OCI related artifacts
+
 ### Recommendation
 
 - File system cache