Document how insignificant parameters work

 * Document how two Tasks with the same params are identical
 * Document how significant=False changes the signature

I feel like a little more documentation might be needed to clear this up though. For example: When using the remote scheduler, if there are two separate clients who both submit workflows that include a Task with the same significant parameters, but different insignificant parameters, what happens when one of the workers gets that Task? Does it just depend on which worker gets the Task and it runs with the params defined in that worker?