Update README.md

Add note about screenshot tests failing.

README.md

@@ -111,7 +111,8 @@ Examples:
 
 To run the tests execute the following gradle tasks: 
 
-- `testDemoDebug` run all local tests against the `demoDebug` variant.
+- `testDemoDebug` run all local tests against the `demoDebug` variant. Screenshot tests will fail
+(see below for explanation). To avoid this, run `recordRoborazziDemoDebug` prior to running unit tests.
 - `connectedDemoDebugAndroidTest` run all instrumented tests against the `demoDebug` variant. 
 
 **Note:** You should not run `./gradlew test` or `./gradlew connectedAndroidTest` as this will execute 
@@ -137,7 +138,7 @@ stored in `modulename/src/test/screenshots`.
 - `compareRoborazziDemoDebug` create comparison images between failed tests and the known correct
 images. These can also be found in `modulename/src/test/screenshots`. 
 
-**Note:** The known correct screenshots stored in this repository are recorded on CI using Linux. Other
+**Note on failing screenshot tests:** The known correct screenshots stored in this repository are recorded on CI using Linux. Other
 platforms may (and probably will) generate slightly different images, making the screenshot tests fail. 
 When working on a non-Linux platform, a workaround to this is to run `recordRoborazziDemoDebug` on the
 `main` branch before starting work. After making changes, `verifyRoborazziDemoDebug` will identify only