docs: add server side redirect and fix NgModule FAQ links (#21487)

PR Close #21487

aio/content/guide/feature-modules.md

@@ -104,7 +104,7 @@ When the CLI generated the `CustomerDashboardComponent` for the feature module,
 
 To see this HTML in the `AppComponent`, you first have to export the `CustomerDashboardComponent` in the `CustomerDashboardModule`. In `customer-dashboard.module.ts`, just beneath the declarations array, add an exports array containing `CustomerDashboardModule`:
 
-<code-example path="feature-modules/src/app/customer-dashboard/customer-dashboard.module.ts" region="customer-dashboard-component" title="src/app/customer-dashboard.module.ts" linenums="false">
+<code-example path="feature-modules/src/app/customer-dashboard/customer-dashboard.module.ts" region="component-exports" title="src/app/customer-dashboard.module.ts" linenums="false">
 </code-example>
 
 

aio/content/guide/ngmodule-faq.md

@@ -338,6 +338,7 @@ Define child routes and let the router load module components into that outlet.
 <hr/>
 
 <a id="q-root-component-or-module"></a>
+
 {@ q-root-component-or-module}
 
 ## Should I add application-wide providers to the root `AppModule` or the root `AppComponent`?
@@ -372,6 +373,7 @@ This means that lazy-loaded modules can't reach them.
 
 <hr/>
 <a id="q-component-or-module"></a>
+
 {@ q-component-or-module}
 
 ## Should I add other providers to a module or a component?
@@ -394,6 +396,7 @@ not the root `AppComponent`.
 <hr/>
 
 <a id="q-why-bad"></a>
+
 {@ q-why-bad}
 
 ## Why is it bad if a shared module provides a service to a lazy-loaded module?

aio/content/guide/sharing-ngmodules.md

@@ -55,7 +55,7 @@ having to import it directly into the `@NgModule` decorator.
 ### Using components vs services from other modules.
 
 There is an important distinction between using another module's component and
-using a service from another module.. Import modules when you want to use
+using a service from another module. Import modules when you want to use
 directives, pipes, and components. Importing a module with services means that you will have a new instance of that service, which typically is not what you need, (typically one wants to reuse an existing service.) Use module imports to control service instantiation. 
 
 The most common way to get a hold of sharedservices is through Angular

aio/firebase.json

@@ -49,6 +49,9 @@
       // aot-compiler.md and metadata.md combined into aot-compiler.md - issue #19510
       {"type": 301, "source": "/guide/metadata", "destination": "/guide/aot-compiler"},
 
+      // ngmodule.md renamed to ngmodules.md
+      {"type": 301, "source": "/guide/ngmodule", "destination": "/guide/ngmodules"}
+
       // service-worker-getstart.md, service-worker-comm.md, service-worker-configref.md
       {"type": 301, "source": "/guide/service-worker-getstart", "destination": "/guide/service-worker-getting-started"},
       {"type": 301, "source": "/guide/service-worker-comm", "destination": "/guide/service-worker-communications"},

aio/ngsw-manifest.json

@@ -19,7 +19,7 @@
   "routing": {
     "index": "/index.html",
     "routes": {
-      "^(?!/docs/ts/latest|/guide/(?:cli-quickstart|metadata|service-worker-(?:getstart|comm|configref))/?$|/styleguide).*/(?!e?plnkr)[^/.]*$": {
+      "^(?!/docs/ts/latest|/guide/(?:cli-quickstart|metadata|ngmodule|service-worker-(?:getstart|comm|configref))/?$|/styleguide).*/(?!e?plnkr)[^/.]*$": {
         "match": "regex"
       }
     }