docs(cheatsheet): add NgModules docs to the cheatsheet

modules/@angular/docs/cheatsheet/ngmodules.md

@@ -0,0 +1,45 @@
+@cheatsheetSection
+NgModules
+@cheatsheetIndex 1
+@description
+{@target ts js}`import { NgModule } from '@angular/core';`{@endtarget}
+
+@cheatsheetItem
+syntax(ts js):
+`@NgModule({ declarations: ... , imports: ..., exports: ..., bootstrap: ...})
+class MyModule {}`|`NgModule`
+description:
+Defines a module that contains components, directives, pipes and providers.
+
+
+@cheatsheetItem
+syntax(ts js):
+`declarations: [MyRedComponent, MyBlueComponent, MyDatePipe]`|`declarations:`
+description:
+List of components, directives and pipes that belong to this module.
+
+@cheatsheetItem
+syntax(ts js):
+`imports: [BrowserModule, SomeOtherModule]`|`imports:`
+description:
+List of modules that are being imported into this module. Everything from the imported modules will
+be available to `declarations` of this module.
+
+@cheatsheetItem
+syntax(ts js):
+`exports: [MyRedComponent, MyDatePipe]`|`exports:`
+description:
+List of components, directives and pipes that will be visible to modules that import this module.
+
+@cheatsheetItem
+syntax(ts js):
+`providers: [MyService, { provide: ... }]`|`providers:`
+description:
+Array of dependency injection providers visible to contents of this module as well as everyone
+importing this module.
+
+@cheatsheetItem
+syntax(ts js):
+`bootstrap: [MyAppComponent]`|`bootstrap:`
+description:
+Array of components to bootstrap when this module is bootstrapped.