[WIP] Complete task-schema.json

[annakrystalli]

Pull request resolves:

• 1

• 5

• 7

• 9 (partially, still waiting for agreement on best approach)

Have also added additional field described in hubDocs and the googledoc. It did raise a question (https://github.com/Infectious-Disease-Modeling-Hubs/hubDocs/issues/13) regarding the target task id which was not present in the docs but is in all the examples and two variables (outcome_variable and outcome_modifier) which were in the docs but not in any of the examples. Would be great to get some clarity on that question :)

Not sure I've captured the submission due description information correctly!

And any feedback on the waffly and perhaps imprecise description fields very welcome!

[annakrystalli]

Thank you for the reviews and commit suggestions @LucieContamin, @nickreich & @elray1 ! And apologies for the messy commit history from accepting them one by one 🤦‍♀️. I'll go ahead and implement some of the agreed changes.

[annakrystalli]

As suggested by @nickreich , merging so we can start afresh using issues.