[Impeller] Update README to point to frame capture docs. (#33796)

diff --git a/impeller/README.md b/impeller/README.md
index 0af6191..13fb037 100644
--- a/impeller/README.md
+++ b/impeller/README.md
@@ -181,5 +181,6 @@
 
 * [Impellers Coordinate System](docs/coordinate_system.md)
 * [How to Setup Xcode for GPU Frame Captures with Metal.](docs/xcode_frame_capture.md)
+* [Learning to Read GPU Frame Captures](docs/read_frame_captures.md)
 * [How to Enable Metal Validation for Command Line Apps.](docs/metal_validation.md)
 * [How Impeller Works Around The Lack of Uniform Buffers in Open GL ES 2.0.](docs/ubo_gles2.md)