Kafka binding documentation

[itsmurugappan]

Fixes #2401

Proposed Changes

• Document for Kafka binding

I have assumed that with 0.15 release , KafkaSource manifests will include the crds for KafkaBinding

Also I published kafka-publisher image into my personal repo and have used it in the example, not sure if this is the right thing.

[mattmoor]

Could we show/include the source snippet used to build the container image you are running?

[itsmurugappan]

Could we show/include the source snippet used to build the container image you are running?

Added a line for the kafka publisher, that I have used the code from here.
Will add for the event display image.

[vaikas]

Thanks for doing this! Few small comments.

[vaikas]

They have to first download this file? Wonder if it would be better to have this use the here document? Or, maybe add a link to this file?
Also, the step says this will create a namespace, but it actually installs kafka?

[itsmurugappan]

In the previous step which displays the yaml, i have added "Describe the size of your Apache Kafka installation in kafka.yaml", in the next step we apply this yaml.

[evankanderson]

/assign @mpetason @vaikas

[vaikas]

/lgtm
/approve

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