Actionable items from `@snoop_llvm` in the tutorial

[Sbozzolo]

I am excited to see that there's a Tutorial on @snoop_llvm, but I am finding the tutorial not very informative. In particular, the tutorial does not explain the relevance of the the data saved in the files and does not tell me how I can interpret the data and take action to reduce LLVM time.

[timholy]

You're right that the docs are just a stub. I've not really used this myself, so I didn't spend the time to explore & document it thoroughly. CC @NHDaly.