accept objects, functions and promises for headers

Signed-off-by: Abhinav Rastogi <abhinav.rastogi@harness.io>

.changeset/violet-dots-relate.md

@@ -2,29 +2,4 @@
 '@backstage/core-components': patch
 ---
 
-Added option to pass additional headers to `<ProxiedSignInPage />`
-
-The <ProxiedSignInPage /> supports signing into Backstage with a Sign Page coming from an external provider e.g. Google IAP, AWS ALB, etc. The component makes requests to a single endpoint `/refresh` on the auth backend to fetch the logged in user session.
-
-If the provider in auth backend expects additional headers such as `x-provider-token`, there is now a way to configure that in `ProxiedSignInPage` using the optional `getHeaders` prop.
-
-Example -
-
-```tsx
-const app = createApp({
-  // ...
-  components: {
-    SignInPage: props => (
-      <ProxiedSignInPage
-        {...props}
-        provider="my-custom-provider"
-        getHeaders={async () => {
-          const someValue = await someFn();
-          return { 'x-some-key': someValue };
-        }}
-      />
-    ),
-  },
-  // ...
-});
-```
+Added option to pass additional headers to `<ProxiedSignInPage />`, which are passed along with the request to the underlying provider