doc: update new default watch flag for ng test

Author: Mathou54

packages/angular/cli/lib/config/schema.json

@@ -699,7 +699,7 @@
             "watch": {
               "type": "boolean",
               "description": "Run build when files change.",
-              "default": false
+              "default": true
             },
             "outputHashing": {
               "type": "string",