docs(lambda-nodejs): improve esbuild monorepo documentation (#18216)

Closes #18175 - see #18175 (comment) for details.

----

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Author: blimmer

packages/@aws-cdk/aws-lambda-nodejs/README.md

@@ -116,6 +116,11 @@ OR
 $ yarn add --dev esbuild@0
 ```
 
+If you're using a monorepo layout, the `esbuild` dependency needs to be installed in the "root" `package.json` file,
+not in the workspace. From the reference architecture described [above](#reference-project-architecture), the `esbuild`
+dev dependency needs to be in `./package.json`, not `packages/cool-package/package.json` or
+`packages/super-package/package.json`.
+
 To force bundling in a Docker container even if `esbuild` is available in your environment,
 set `bundling.forceDockerBundling` to `true`. This is useful if your function relies on node
 modules that should be installed (`nodeModules` prop, see [below](#install-modules)) in a Lambda
@@ -253,7 +258,7 @@ new lambda.NodejsFunction(this, 'my-handler', {
 });
 ```
 
-Note: A [`tsconfig.json` file](https://www.typescriptlang.org/docs/handbook/tsconfig-json.html) is required 
+Note: A [`tsconfig.json` file](https://www.typescriptlang.org/docs/handbook/tsconfig-json.html) is required
 
 ## Customizing Docker bundling