update Injecting fetch docs

packages/platform/README.md

@@ -755,19 +755,24 @@ Output:
 To test HTTP requests, you can inject a mock fetch implementation.
 
 ```ts
-import * as Http from "@effect/platform/HttpClient"
+import {
+  HttpClient,
+  HttpClientRequest,
+  HttpClientResponse
+} from "@effect/platform"
 import { Effect, Layer } from "effect"
 import * as assert from "node:assert"
 
 // Mock fetch implementation
-const FetchTest = Layer.succeed(Http.client.Fetch, () =>
+const FetchTest = Layer.succeed(HttpClient.Fetch, () =>
   Promise.resolve(new Response("not found", { status: 404 }))
 )
 
 // Program to test
-const program = Http.request
-  .get("https://www.google.com/")
-  .pipe(Http.client.fetch, Http.response.text)
+const program = HttpClientRequest.get("https://www.google.com/").pipe(
+  HttpClient.fetch,
+  HttpClientResponse.text
+)
 
 // Test
 Effect.gen(function* () {