Update samples for next wave of releases

[kaerm]

Make sure there are enough samples covering the most important scenarios and more advanced examples in the repo for the following packages:

• storage-file-share
• keyvault-certificates

cc: @ramya-rao-a

[ramya-rao-a]

#5109 is tracking the sample updates to all 3 storage libraries
We have the important scenarios for keyvault certificates already in https://github.com/Azure/azure-sdk-for-js/tree/master/sdk/keyvault/keyvault-certificates/samples/javascript.

@jonathandturner Was there plans to add any more samples among the keyvault crew? If not, then go ahead and close this issue

[kaerm]

Just want to make sure all elements are in place. If you are already done I'll be extremely happy if you close so that I can take it off my list @ramya-rao-a :)