Starred the two I liked
Comma for clarity
Clarified that you have to end with the tag in a feature block
Clarified that in a class to class replacement, you need to have the same number of glyphs in the class
Some way to highlight keywords?
Small caps can be tricky, should there be a note about what to do with special cases where you can't trust that proper case conversion will be done?
Fixed typo
I think you need this section, but I would perhaps think of it as hints and tips; ways to avoid common pitfalls that don't fall neatly into the above anywhere.