message: fix incorrect class name on backend
diff: @@ -22,7 +22,7 @@ do this by creating a file called `packages/backend/src/plugins/techInsights.ts`
  ```ts
  import {
  createRouter,
  - DefaultTechInsightsBuilder,
  + buildTechInsightsContext,
  } from '@backstage/plugin-tech-insights-backend';
  import { Router } from 'express';
  import { PluginEnvironment } from '../types';
  @@ -33,7 +33,7 @@ export default async function createPlugin({
  discovery,
  database,
  }: PluginEnvironment): Promise<Router> {
  - const builder = new DefaultTechInsightsBuilder({
  + const builder = buildTechInsightsContext({
  logger,
  config,
  database,
  