Standardize format of kubectl. Fix typo with display of k8s-workertoo…

[adrianparker]

A couple of tiny tweaks. 1. On this page we usually format the term kubectl with backticks, but in one place we weren't, so applied format there too. 2. We had a typo with the backticks location on the k8s-worker link, this meant our markdown was showing; changed so that link is now displayed nicely.

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