Update the Pipelines "Getting Started" page with links to other basic guides

[hbelmiro]

This must be done after #3737 gets merged.

Update the "Getting Started" with a link to the "Connect the Pipelines SDK to Kubeflow Pipelines" guide:
https://deploy-preview-3737--competent-brattain-de2d6d.netlify.app/docs/components/pipelines/user-guides/core-functions/connect-api/

Also, add a link to the new "User Guides" section, and point them at the most important topics in a logical order that "reads like a story" for new users.

Contextualization:

• Restructured Kubeflow Pipelines docs #3737 (comment)
• Restructured Kubeflow Pipelines docs #3737 (comment)

/area pipelines