Added Contributor Setup guide and Podrick docforge task

[n-boshnakov]

What this PR does / why we need it:
This PR:

• Adds a Contributor Setup topic
• Adds an Issues topic
• Adds a task to help users get accustomed to working with docforge

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Release note:

Added Contributor Setup guide
Added Podrick task

[gardener-prow]

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