Updates to IntroToKubernetes

[larryclaman]

I recently used the IntroToKubernetes content to run a Kubernetes hack with a customer, and I made a large number of edits & updates in the process. I will be feeding these back as a series of Pull Requests, and I'm hoping these will be approved and rolled back into the release. Please contact me with any questions.

cc'ing @gfilicetti and @micya as they were the two most recent contributors to the Kubernetes hack content.
cc @jrzyshr

[larryclaman]

PRs:

Challenge	PR	Status	Notes
Ch01 Containers	#216	4/5/21: needs rework	significant edit; I provide dockerfiles to the students rather than having them create their own. Read the PR notes for my reasoning.
Ch03 Intro to K8S	#207	ready for review 5-17
Ch04 Deployments	#209	wip
Ch05 Scaling	#210	merged
Ch06 Deploy Mongo	#211	4/22: merged
Ch07 Updates & Rollbacks	#212	merged
Ch08 Storage	#213	4/22: Merged	Significant update; I refactored out the custom storage class as it's no longer needed
Ch10 Networking	#214	4/22: merged

that's it for now!

[larryclaman]

These have been incorporated via PR's