[webauthn] incosistent concatenation symbols - notational conventions section?

equalsJeffH has just created a new issue for https://github.com/w3c/webauthn:

== incosistent concatenation symbols - notational conventions section? ==
in [figure 2](https://w3c.github.io/webauthn/#fig-signature) we use a double-vertical-bar`||` symbol to indicate concatenation, but elsewhere in spec we use a single-vertical-bar `|` to also indicate concatenation.  Perhaps we should consistently use a double-vertical-bar`||` symbol. 

Also we do not have a section on notational conventions. perhaps we should.


Please view or discuss this issue at https://github.com/w3c/webauthn/issues/562 using your GitHub account