Update scaffolder installation instructions

Co-authored-by: Patrik Oldsberg <poldsberg@gmail.com>

docs/features/software-templates/installation.md

@@ -33,7 +33,28 @@ it doesn't.
 Add the following entry to the head of your `packages/app/src/plugins.ts`:
 
 ```ts
-export { plugin as ScaffolderPlugin } from '@backstage/plugin-scaffolder';
+export { scaffolderPlugin } from '@backstage/plugin-scaffolder';
+```
+
+Next we need to install the three pages that the scaffolder plugin provides. You
+can choose any name for these routes, but we recommend the following:
+
+```tsx
+import { TemplateIndexPage, TemplatePage, TaskPage } from '@backstage/plugin-scaffolder';
+
+// Add to the top-level routes, directly within <FlatRoutes>
+<Route path="/create" element={<TemplateIndexPage />} />
+<Route path="/create/templates/:templateName" element={<TemplatePage />} />
+<Route path="/create/tasks/:taskId" element={<TaskPage />} />
+```
+
+You may also want to add a link to the template index page to your sidebar:
+
+```tsx
+import CreateComponentIcon from '@material-ui/icons/AddCircleOutline';
+
+// Somewhere within the <Sidebar>
+<SidebarItem icon={CreateComponentIcon} to="create" text="Create..." />;
 ```
 
 This is all that is needed for the frontend part of the Scaffolder plugin to
@@ -66,29 +87,26 @@ following contents to get you up and running quickly.
 import {
   CookieCutter,
   createRouter,
-  FilePreparer,
-  GithubPreparer,
-  GitlabPreparer,
   Preparers,
   Publishers,
-  GithubPublisher,
-  GitlabPublisher,
   CreateReactAppTemplater,
   Templaters,
-  RepoVisibilityOptions,
+  CatalogEntityClient,
 } from '@backstage/plugin-scaffolder-backend';
-import { Octokit } from '@octokit/rest';
-import { Gitlab } from '@gitbeaker/node';
+import { SingleHostDiscovery } from '@backstage/backend-common';
 import type { PluginEnvironment } from '../types';
 import Docker from 'dockerode';
+import { CatalogClient } from '@backstage/catalog-client';
 
 export default async function createPlugin({
   logger,
   config,
+  database,
 }: PluginEnvironment) {
   const cookiecutterTemplater = new CookieCutter();
   const craTemplater = new CreateReactAppTemplater();
   const templaters = new Templaters();
+
   templaters.register('cookiecutter', cookiecutterTemplater);
   templaters.register('cra', craTemplater);
 
@@ -96,12 +114,21 @@ export default async function createPlugin({
   const publishers = await Publishers.fromConfig(config, { logger });
 
   const dockerClient = new Docker();
+
+  const discovery = SingleHostDiscovery.fromConfig(config);
+  const entityClient = new CatalogEntityClient({ discovery });
+  const catalogClient = new CatalogClient({ discoveryApi: discovery });
+
   return await createRouter({
     preparers,
     templaters,
     publishers,
     logger,
+    config,
     dockerClient,
+    entityClient,
+    database,
+    catalogClient,
   });
 }
 ```