docs: add --scope to npm init usage (#20373)

PR-URL: #20373
Credit: @jdalton
Reviewed-By: @zkat

Author: jdalton

lib/init.js

@@ -13,7 +13,7 @@ var usage = require('./utils/usage')
 
 init.usage = usage(
   'init',
-  '\nnpm init [--force|-f|--yes|-y]' +
+  '\nnpm init [--force|-f|--yes|-y|--scope]' +
   '\nnpm init <@scope> (same as `npx <@scope>/create`)' +
   '\nnpm init [<@scope>/]<pkg> (same as `npx [<@scope>/]create-<pkg>`)'
 )