Write advisory document on how to run an OSS election

[jberkus]

Per today's Gov meeting, more TBD.

[jberkus]

Summary:

The people process of running an election, whether you use CIVS, Helios, or Elekto, is pretty much the same, and there's a fairly well-tested way to do it by several CNCF projects. It would make sense for me, as the perennial election committee member, to write that up as an advisory for projects.

Prerequisites: (1) finish elekto deployment docs (2) get access to the LF elections thing as well

[aliok]

Related: #546

This task is about creating the documentation, #546 is about helping projects apply the advisory from the to-be-created document.