Add note about import statements following shuffling.

README.md

@@ -13,9 +13,9 @@ framework for accessing JSON APIs.
 This is the recommended library for accessing JSON-based Google APIs for iOS,
 macOS, tvOS, and watchOS applications.
 
-**To get started** with Google APIs and the Objective-C client library, Read the
-[USING.md](https://github.com/google/google-api-objectivec-client-for-rest/blob/main/USING.md).
-The
+**To get started** with Google APIs and the Objective-C client library, please read
+[USING.md](https://github.com/google/google-api-objectivec-client-for-rest/blob/main/USING.md)
+for detailed information. The
 [example applications](https://github.com/google/google-api-objectivec-client-for-rest/tree/main/Examples)
 can also help answer some questions, but there isn't an example for every
 service as there are just to many services.

USING.md

@@ -83,6 +83,17 @@ If you are generating code for your own APIs, then add
 `GoogleAPIClientForRESTCore` to get the supporting runtime and then manually add
 the generated sources to your Xcode project.
 
+### `#import`s and `@import`s
+
+Since CocoaPods and SwiftPM use different models for how things are built, the
+module names for `@import` directives will be specific to each packaging system.
+
+However, if consuming this library via Objective-C, all the packages export
+their headers as _GoogleAPIClientForREST/HEADER.h_, so you can always `#import`
+them as a framework import and that will work with either packaging system,
+i.e. - `#import <GoogleAPIClientForREST/GTLRService.h` and
+`#import <GoogleAPIClientForREST/GTLRYouTube.h`.
+
 ### Dependencies
 
 The Google APIs Library for Objective-C for REST uses the prefix `GTLR`.