KFP - Updated the documentation regarding metrics (kubeflow#2171)

* [WIP] Updated the documentation regarding metrics

* Resolved the feedback

* Added an alternative python component example

* Added a component.yaml example

* Apply suggestions from code review

Co-authored-by: 8bitmp3 <[email protected]>

* Update content/en/docs/pipelines/sdk/pipelines-metrics.md

Co-authored-by: 8bitmp3 <[email protected]>

Co-authored-by: 8bitmp3 <[email protected]>