build: open correct file in Stackblitz editor

The path for the file that Stackblitz should open in the editor was wrong which meant that it would open any random file. These changes correct the path.

Author: crisbeto

docs/src/app/shared/stackblitz/stackblitz-writer.ts

@@ -53,9 +53,6 @@ export const TEMPLATE_FILES = [
   'src/test.ts',
 ];
 
-const PROJECT_TAGS = ['angular', 'material', 'cdk', 'web', 'example'];
-const PROJECT_TEMPLATE = 'node';
-
 /**
  * Type describing an in-memory file dictionary, representing a
  * directory and its contents.
@@ -82,7 +79,7 @@ export class StackBlitzWriter {
     // and the file requests can cause excessive change detections.
     return this._ngZone.runOutsideAngular(async () => {
       const files = await this._buildInMemoryFileDictionary(data, exampleId, isTest);
-      const exampleMainFile = `src/app/${data.indexFilename}`;
+      const exampleMainFile = `src/example/${data.indexFilename}`;
 
       return () => {
         this._openStackBlitz({
@@ -112,8 +109,8 @@ export class StackBlitzWriter {
         title,
         files,
         description,
-        template: PROJECT_TEMPLATE,
-        tags: PROJECT_TAGS,
+        template: 'node',
+        tags: ['angular', 'material', 'cdk', 'web', 'example'],
       },
       {openFile},
     );