Update template-oms.parameters.json

[Carl-Hugo]

Applied the Log Analytics pricing model change of April 2018 fix.

[slapointe]

We know this changed recently, it would be a good thing to be this value by default in the parameters file. It would be more future proof IMO.

This requires a change in the Step1 documentation for those still running on the old pricing model (because you're not forced to switch).

Please also update the documentation from PerGB2018 to Free, adapt the screen shots and error message and we will let this change go through.

[slapointe]

Do you want to perform the changes @Carl-Hugo ? If not, we'll leave it this way and reject the PR.

[Carl-Hugo]

This is on my todo list. I will do my best to complete it before next year Bootcamp.