Change third metadata line to domain

[istathar]

We've realized that "template" really refers to the layout and styling used to present a formatted technique when rendered. There are different kinds of Technique, different application domains, and so we rename the metadata line which indicates which kind of procedure a Technique document is to become the "domain line".

Internally we change the names of the domain and range genus in the signature of a procedure declaration to be depends and provides.

Implements:

• Rename template to domain specification#8

[jaesharp]

https://www.debian.org/doc/debian-policy/ch-relationships.html ... this can get pretty complicated, so we should watch out for these issues and/or keep them in mind as we start using 'requires' and 'provides'

[istathar]

Yeah. Right now it's a purely internal name. Could have been from and to but your suggestion makes for petty good variable names.