docs(config): document no- prefixed configs more clearly

[darcyclarke]

Summary

Currently there doesn't seem to be any documentation around the no- prefix functionality that exists for all of our configs (ie. defining the config with the prefix sets the value of the config to false).

• add a section outlining this behavior in https://docs.npmjs.com/cli/v7/using-npm/config

[wraithgar]

One of the things we did was add --no- to the boolean examples for given commands:

~ $ npm repo --help
npm repo

Open package repository page in the browser

Usage:
npm repo [<pkgname> [<pkgname> ...]]

Options:
[--no-browser|--browser <browser>]
[-w|--workspace <workspace-name> [-w|--workspace <workspace-name> ...]]
[-ws|--workspaces]

We can probably do something similar to the long-form help of booleans?