I don't have access to the actual content of the SKILL.md file you referenced, so I can only work from the name and description. This appears to be a structured framework for conducting post-mortem analyses after incidents, projects, or deployments. You'd use it when something went wrong (or right) and you need to document what happened, why it happened, and what to do next time. The value is in having a consistent format so your team actually learns from failures instead of just moving on. Post-mortems are one of those things everyone knows they should do but often skip or rush through, so having a template that prompts the right questions makes it more likely you'll actually follow through.
npx skills add https://github.com/alirezarezvani/claude-skills --skill post-mortem