docs: clarify that remote-entries.json is user-produced (#51)

Add an explicit note that remote manifest files are NOT generated by
webpack or ModuleFederationPlugin — users must produce and host them
themselves alongside their builds. Split the per-remote vs registry
manifest formats into clearly labeled subsections.

Author: steven-pribilinskiy

README.md

@@ -210,6 +210,19 @@ The `remoteEntryUrls` option is a simple key-value map of remote names and their
 
 ### Remote Manifest files
 
+> **Note:** Remote manifest files (e.g. `remote-entries.json`, `mfe-app-1-remote-entry.json`)
+> are **not** generated by webpack or `ModuleFederationPlugin`. They are plain JSON files that
+> **you produce and host yourself** — typically as part of your CI/deployment pipeline, alongside
+> the `remoteEntry.js` of each microapp. The filename is arbitrary; `remote-entries.json` is just
+> the convention used in these examples.
+>
+> Their purpose is to let the host discover where each remote's `remoteEntry.js` lives in a given
+> environment without hardcoding URLs. This plugin fetches them at build time to learn the
+> remotes' base URLs and download their `.d.ts` files from `<baseUrl>/@types/index.d.ts`.
+>
+> A minimal way to generate one is to write a small post-build script that emits a JSON file
+> containing the public URL of the just-built `remoteEntry.js` and uploads it next to the bundle.
+
 Manifest files, when provided, are fetched every time the types are downloded.
 
 Example of a configuration:
@@ -232,14 +245,19 @@ new ModuleFederationTypesPlugin({
 })
 ```
 
-It's expected that a JSON will contain an object with a `url` property:
+#### Per-remote manifest format
+
+For each entry in `remoteManifestUrls` other than `registry`, the JSON is expected to be an
+object with a `url` property pointing at that remote's `remoteEntry.js`:
 
 ```json
 {
   "url": "https://assets.mydomain.com/mfe-app/remoteEntry.js"
 }
 ```
 
+#### Registry manifest format
+
 For the `registry` field in `remoteManifestUrls` or for the single `remoteManifestUrl` option,
 multiple remote entry URLs can be substituted in a single JSON file.
 Depending on your architecture, this could be the only URL that you need to specify.