Description of problem:

In Seldon install document there are some broken links to be replaces:

1. Serverless Operator. The right link might be this  new (instead of the broken  one)
2. knative eventing. new one instead of broken one
3. knative serving. new one instead of broken one
4. Seldon Community Slack channel: link not active anymore

Moreover, all the links to Openshift documentation points to version 4.7 and then those should be changed to point to v4.9

Prerequisites (if any, like setup, operators/versions):

Steps to Reproduce

1. Open Seldon Deploy Install document

Actual results:

Expected results:

Reproducibility (Always/Intermittent/Only Once):

Build Details:

Workaround:

Additional info: