Update Kubeflow diagrams with Spark Operator and Model Registry

[andreyvelich]

I updated Kubeflow diagrams with Spark Operator and Model Registry, since we already have these components on Kubeflow website.

/assign @kubeflow/wg-data-leads @kubeflow/kubeflow-steering-committee @vikas-saxena02

[rimolive]

/lgtm

[tarilabs]

Thank you so much @andreyvelich

In content/en/docs/started/images/kubeflow-intro-diagram.drawio.svg
I would suggest rename the in-parenthesis from:
(ML Metadata)
to:
(Model Metadata)

so to keep the generic scope intended by the parenthesis, and avoid potential confusion with the "MLMD" (library/project).

wdyt ?

[thesuperzapper]

@andreyvelich I agree that we should say "Model Metadata" rather than "ML Metadata" (which is the name of an actual project that we use as a dependency: https://github.com/google/ml-metadata

Also, can you fix the alignment problem on the "Feast" square, it drives me crazy:

[vikas-saxena02]

great work @andreyvelich you just depicted my precise thoughts here.

/approve

[vikas-saxena02]

/approve

[andreyvelich]

Sounds good, updated.
/assign @tarilabs @thesuperzapper

[tarilabs]

/lgtm

thank you so much

[andreyvelich]

/approve

[google-oss-prow]

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