docs: remove incorrect watchPlugins: false references

Remove all references to the incorrect `config.watchPlugins: false`
requirement that was believed necessary for Headlamp v0.39.0+.

Investigation revealed that plugins work correctly with the default
`watchPlugins: true` setting. The earlier documentation was based on
a misunderstanding of the plugin loading mechanism.

Changes:
- Remove watchPlugins: false from all YAML configuration examples
- Remove warning sections about watchPlugins requirement
- Update troubleshooting guides to focus on actual issues
- Simplify installation instructions by removing unnecessary config

Files updated:
- README.md (main installation docs and troubleshooting table)
- docs/DEPLOYMENT.md
- docs/TROUBLESHOOTING.md
- docs/getting-started/* (quick-start, installation, prerequisites)
- docs/deployment/* (helm, production)
- docs/troubleshooting/* (common-issues, README)
- Multiple other doc files formatted by prettier

This cleanup ensures ArtifactHub and GitHub documentation show
correct, simplified installation instructions.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

docs/troubleshooting/network-problems.md

@@ -87,7 +87,7 @@ dashboard:
   enabled: true
   env:
     - name: CORS_ALLOWED_ORIGINS
-      value: "https://headlamp.example.com"
+      value: 'https://headlamp.example.com'
 ```
 
 Test CORS headers: