build(aio): move doc-gen stuff from angular.io (#14097)

docs/content/cheatsheet/ngmodules.md

@@ -0,0 +1,58 @@
+@cheatsheetSection
+NgModules
+@cheatsheetIndex 1
+@description
+{@target ts}`import { NgModule } from '@angular/core';`{@endtarget}
+{@target js}Available from the `ng.core` namespace{@endtarget}
+
+@cheatsheetItem
+syntax(ts):
+`@NgModule({ declarations: ..., imports: ...,
+     exports: ..., providers: ..., bootstrap: ...})
+class MyModule {}`|`NgModule`
+description:
+Defines a module that contains components, directives, pipes, and providers.
+
+syntax(js):
+`ng.core.NgModule({declarations: ..., imports: ...,
+     exports: ..., providers: ..., bootstrap: ...}).
+Class({ constructor: function() {}})`
+description:
+Defines a module that contains components, directives, pipes, and providers.
+
+@cheatsheetItem
+syntax:
+`declarations: [MyRedComponent, MyBlueComponent, MyDatePipe]`|`declarations:`
+description:
+List of components, directives, and pipes that belong to this module.
+
+@cheatsheetItem
+syntax(ts):
+`imports: [BrowserModule, SomeOtherModule]`|`imports:`
+description:
+List of modules to import into this module. Everything from the imported modules
+is available to `declarations` of this module.
+
+syntax(js):
+`imports: [ng.platformBrowser.BrowserModule, SomeOtherModule]`|`imports:`
+description:
+List of modules to import into this module. Everything from the imported modules
+is available to `declarations` of this module.
+
+@cheatsheetItem
+syntax:
+`exports: [MyRedComponent, MyDatePipe]`|`exports:`
+description:
+List of components, directives, and pipes visible to modules that import this module.
+
+@cheatsheetItem
+syntax:
+`providers: [MyService, { provide: ... }]`|`providers:`
+description:
+List of dependency injection providers visible both to the contents of this module and to importers of this module.
+
+@cheatsheetItem
+syntax:
+`bootstrap: [MyAppComponent]`|`bootstrap:`
+description:
+List of components to bootstrap when this module is bootstrapped.