Add examples for ProxySetHeaders Annotation

[AlexFenlon]

Proposed changes

Adds examples for both standard and mergeable ingress for the ProxySetHeaders Annotation

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[AlexFenlon]

@ADubhlaoich I added link to the examples here but I am not sure if it is correct, would the relative path be better instead of the full link?

[jjngx]

🚀