1. General Tolernce:....
2. "bla bla "
Without the "pay attention" or "notice" etc'
you can put a triangle flag wherever you want special attention.
We use various terms depending on the mood of the engineer when they are making the drawing. We have used "Note blah blah..." and "Make sure blah blah..." and "Verify blah blah...".
But in your case for a symmetry note, I don't think you need anything, just "2. The part is symmetric..." And the CL symbol sort of acts as the note flag so I don't think you need a separate flag.