Added Post Incident Practices module

[tom-halpin]

Proposed changes

Added Post Incident Practices module

Types of changes

What types of changes does your code introduce to Online DevOps Dojo? Put an x in the boxes that apply

• [ ] Bug fix (non-breaking change which fixes an issue)
• [X] New feature (non-breaking change which adds functionality)
• [ ] Code style update (formatting, renaming)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Workflow change
• [ ] Documentation update (if none of the other choices apply)

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• [X] I have read the CONTRIBUTING doc.
• [X] Lint passes locally with my changes.
• [X] I have added necessary documentation (if appropriate).
• [X] Any dependent changes have been merged and published in downstream modules

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

[tom-halpin]

@cpswan @ojacques @pberthonneau open sourcing Post Incident Practices module by way of a small thank you to the community given the very positive reaction to the Dojo since we launched it.