refine public documentations

Author: ChaoqunCHEN

packages-exp/installations-exp/src/api/get-installations.ts

@@ -20,7 +20,7 @@ import { FirebaseInstallations } from '@firebase/installations-types-exp';
 import { _getProvider } from '@firebase/app-exp';
 
 /**
- * Returns a Firebase Installation instance for the given app.
+ * Returns an instance of FirebaseInstallations associated with the given FirebaseApp instance.
  *
  * @public
  */

packages-exp/installations-exp/src/api/get-token.ts

@@ -24,7 +24,7 @@ import {
 import { FirebaseInstallations } from '@firebase/installations-types-exp';
 
 /**
- * Returns an authentication token for the current Firebase Installation.
+ * Returns an Installation auth token, identifying the current Firebase Installation.
  *
  * @public
  */

packages-exp/installations-exp/src/api/on-id-change.ts

@@ -20,7 +20,7 @@ import { FirebaseInstallationsImpl } from '../interfaces/installation-impl';
 import { FirebaseInstallations } from '@firebase/installations-types-exp';
 
 /**
- * An user defined callback function that takes action when Installations ID changes.
+ * An user defined callback function that gets called when Installations ID changes.
  *
  * @public
  */

packages-exp/installations-types-exp/index.d.ts

@@ -16,7 +16,7 @@
  */
 
 /**
- * A Firebase Installation instance which is a required argument for all Firebase Installations operations.
+ * Public interface of the FirebaseInstallations SDK.
  *
  * @public
  */