Macro designators listed but not explained

[locks]

In https://doc.rust-lang.org/reference.html#macro-by-example the various designators available for macro construction are listed, but they are not explained. The closest I could find was https://danielkeep.github.io/practical-intro-to-macros.html:

I am willing to take a stab at it with some guidance.

[steveklabnik]

I am bad at macros, but yes, this should be explained more.