docs: edit build description

Author: jbogarthyde

packages/angular/cli/commands/build-long.md

@@ -1,10 +1,11 @@
-Uses the Webpack build tool, with default target environment and build options specified in the workspace configuration file, `angular.json`.
+Uses the Webpack build tool, with default configuration options specified in the workspace configuration file, `angular.json`, or with a named alternative configuration. 
+A "production" configuration is created by default when you use the CLI to create the project, and you can use that configuration by specifying the `--prod` option.
 
-You can override the configuration defaults by specifying an option on the command line. 
+The configuration options generally correspond to the command options.
+You can override individual configuration defaults by specifying the corresponding options on the command line. 
 The command can accept option names given in either dash-case or camelCase.
 Note that in the configuration file, you must specify names in camelCase.
 
-The configuration options generally correspond to the command options.
 Some additional options can only be set through the configuration file,
 either by direct editing or with the `ng config` command.
 These include `assets`, `styles`, and `scripts` objects that provide runtime-global resources to include in the project.