Meta is the most fundamental section. To flesh this out, we discuss references. Primitives are briefly mentioned by pointing to pkgbits,
where they will be defined using a similar grammar.

Change-Id: I7abd899f38fad4cc5caf87ebfc7aa1b1985b17d4
Reviewed-on: https://go-review.googlesource.com/c/go/+/671176


Auto-Submit: Mark Freeman <mark@golang.org>
TryBot-Bypass: Mark Freeman <mark@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>