Throw identify-node-by-nickname down the memory hole

Authorities are no longer voting on Named, so specifying nodes by
nickname isn't a clever thing to do.  (Not that it ever was!)  So
remove the documentation that suggests that you should do it.

Additionally, add proper cross-references to our __node__ lists, and
explain about the optional $ before identity digests.

Also, the oxford comma: endorsed by Steven Pinker, my spouse, and my
11th grade English teacher.

Closes 13381.