Add requirements to note that paramiko is needed

I have no idea whether projects in infra use requirements.txt,
however, I was surprised to run the script and have it fail due to
a missing module and no documentation about it being needed to be
installed :)

Your feedback welcome!

Change-Id: I0f0833a67004bfcc7649083a201086337a6d4b81
Merge "Add requirements to note that paramiko is needed"