Add more doc linking the material and cupertino refresh controls (#15842)
* Add more doc linking the material and cupertino refresh controls
* review
diff --git a/packages/flutter/lib/src/cupertino/refresh.dart b/packages/flutter/lib/src/cupertino/refresh.dart
index 9664865..7a76a47 100644
--- a/packages/flutter/lib/src/cupertino/refresh.dart
+++ b/packages/flutter/lib/src/cupertino/refresh.dart
@@ -242,7 +242,9 @@
/// Only one refresh can be triggered until the previous refresh has completed
/// and the indicator sliver has retracted at least 90% of the way back.
///
-/// Can only be used in downward scrolling vertical lists.
+/// Can only be used in downward-scrolling vertical lists that overscrolls. In
+/// other words, refreshes can't be triggered with lists using
+/// [ClampingScrollPhysics].
///
/// See also:
///
diff --git a/packages/flutter/lib/src/material/refresh_indicator.dart b/packages/flutter/lib/src/material/refresh_indicator.dart
index 19792f4..2bc78da 100644
--- a/packages/flutter/lib/src/material/refresh_indicator.dart
+++ b/packages/flutter/lib/src/material/refresh_indicator.dart
@@ -74,7 +74,12 @@
///
/// * <https://material.google.com/patterns/swipe-to-refresh.html>
/// * [RefreshIndicatorState], can be used to programmatically show the refresh indicator.
-/// * [RefreshProgressIndicator].
+/// * [RefreshProgressIndicator], widget used by [RefreshIndicator] to show
+/// the inner circular progress spinner during refreshes.
+/// * [CupertinoRefreshControl], an iOS equivalent of the pull-to-refresh pattern.
+/// Must be used as a sliver inside a [CustomScrollView] instead of wrapping
+/// around a [ScrollView] because it's a part of the scrollable instead of
+/// being overlaid on top of it.
class RefreshIndicator extends StatefulWidget {
/// Creates a refresh indicator.
///
