docs(@angular-devkit/schematics-cli): Add README

This commit adds a README for the package.

(cherry picked from commit 07bf174)

Author: kyliau

packages/angular_devkit/schematics_cli/README.md

@@ -0,0 +1,49 @@
+# Schematics CLI
+
+This package contains the executable for running a [Schematic](/packages/angular_devkit/schematics/README.md).
+
+# Usage
+
+```
+$ schematics [CollectionName:]SchematicName [options, ...]
+
+By default, if the collection name is not specified, use the internal collection provided
+by the Schematics CLI.
+
+Options:
+    --debug             Debug mode. This is true by default if the collection is a relative
+                        path (in that case, turn off with --debug=false).
+
+    --allow-private     Allow private schematics to be run from the command line. Default to
+                        false.
+
+    --dry-run           Do not output anything, but instead just show what actions would be
+                        performed. Default to true if debug is also true.
+
+    --force             Force overwriting files that would otherwise be an error.
+
+    --list-schematics   List all schematics from the collection, by name. A collection name
+                        should be suffixed by a colon. Example: '@angular-devkit/schematics-cli:'.
+
+    --no-interactive    Disables interactive input prompts.
+
+    --verbose           Show more information.
+
+    --help              Show this message.
+
+Any additional option is passed to the Schematics depending on its schema.
+```
+
+# Examples
+
+1. Create a new NPM package that contains a blank schematic.
+
+```sh
+$ schematics blank <name>
+```
+
+2. Walkthrough example that demonstrates how to build a schematic.
+
+```sh
+$ schematics schematic --name <name>
+```

packages/angular_devkit/schematics_cli/bin/schematics.ts

@@ -336,7 +336,7 @@ function getUsage(): string {
 
       --help              Show this message.
 
-  Any additional option is passed to the Schematics depending on
+  Any additional option is passed to the Schematics depending on its schema.
   `;
 }