Add placeholder text to templates in the text editor

Aha! allows me to create templates for my features (and hopefully one day for notes). My feature templates often include instructions for users. I typically style this a certain way so the user knows it's just help text. It would be great if I could make this placeholder text that automatically disappeared whenever someone typed in a pre-set area. This would make it so my users don't have to delete help text when completing a template.