docs: fix purpose description of "builders.json" (angular#36830)

PR Close angular#36830

Author: shmool

aio/content/guide/cli-builder.md

@@ -42,7 +42,7 @@ For example, your `myBuilder` folder could contain the following files.
 | `src/my-builder.ts`      | Main source file for the builder definition. |
 | `src/my-builder.spec.ts` | Source file for tests. |
 | `src/schema.json`        | Definition of builder input options. |
-| `builders.json`          | Testing configuration. |
+| `builders.json`          | Builders definition. |
 | `package.json`           | Dependencies. See https://docs.npmjs.com/files/package.json. |
 | `tsconfig.json`          | [TypeScript configuration](https://www.typescriptlang.org/docs/handbook/tsconfig-json.html). |