Document "this instance - total self"

Just started using speedscope, thanks for sharing it, it's already been helpful. What are the fields in the bottom left corner?

Begin with the bottom-left UI area mentioned in the issue and identify each displayed field. Check how those values are presented and add documentation explaining what they mean. Done means a newcomer can understand all of the bottom-left fields without asking the same question.

Written by the indexing model from the issue text.