docs: make "runtime" a word only as a name for the package.

docs: make "runtime" a word only as a name for the package.

Computer people have an agglutinating streak that I like to resist.
As a time of execution: run time.
As an adjective: run-time.
As a noun: run-time support/code/library.

Signed,
Mr. Pedant.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4252048