k8s operator doc tweaks

[trentm]

@eedugon Some minor tweaks to the k8s operator docs that I noticed while reviewing #59

• Correction (I think) to the namespace used in some kubectl commands in the Java and Python docs
• Unfortunately my editor removes trailing whitespace and there were some in these docs, so the diff will be smaller if you hide whitespace differences.
• Remove a duplicate header in the python doc.

[eedugon]

Great catches, thanks a lot!!!
LGTM :)

[eedugon]

Btw, another doc where your insights and review would be very useful is the generic docs/kubernetes/operator/instrumenting-applications.md. That one has the links to the language specific docs that we've been working with recently.