Request debug and indent macro declarations

Add a subsection to Macros which requests indent declarations when
necessary, and debug declarations always.

edebug's default behavior is to assume "no arguments are evaluated", which is probably the opposite of the most common case. So it seems fit that every macro should declare whether its arguments are meant for instrumentation.

I believe this would be a good addition to the guide. Debug and indent are, by far, the most used declarations and they make for a better experience when people are making use of the macro.

Let me know if you think it's too long, kinda wrong, or just plain rubbish.