docs: documentation for contribution of change

Signed-off-by: Tim Klever <tim.v.klever@aexp.com>

.changeset/eleven-beans-relax.md

@@ -0,0 +1,9 @@
+---
+'@backstage/release-manifests': patch
+---
+
+This expands the configurability of `release-manifests` to pave the road for more configuration options in the `cli`.
+
+Specifically it allows the specification of mirrored, proxied, or air-gapped hosts when upgrading across releases when
+working in restricted or heavily governed development environments (common in large enterprises and government
+entities).

packages/release-manifests/report.api.md

@@ -11,6 +11,14 @@ export function getManifestByReleaseLine(
 // @public
 export type GetManifestByReleaseLineOptions = {
   releaseLine: string;
+  fetch?: (
+    url: string,
+    options?: {
+      signal?: AbortSignal;
+    },
+  ) => Promise<Pick<Response, 'ok' | 'status' | 'text' | 'json' | 'url'>>;
+  gitHubRawBaseUrl?: string;
+  versionsBaseUrl?: string;
 };
 
 // @public
@@ -27,6 +35,8 @@ export type GetManifestByVersionOptions = {
       signal?: AbortSignal;
     },
   ) => Promise<Pick<Response, 'status' | 'json' | 'url'>>;
+  gitHubRawBaseUrl?: string;
+  versionsBaseUrl?: string;
 };
 
 // @public