HDR: Update experimental_setEnableHdrEditing javadoc.

Previously, this feature interpreted SDR signals as HDR when called. Now, only HDR
streams are interpreted as HDR, so the javadoc should be updated. Not yet removing
this method, as there are still some loose ends to finish up (ex. PQ support, e2e
tests).

PiperOrigin-RevId: 466425738

library/transformer/src/main/java/com/google/android/exoplayer2/transformer/TransformationRequest.java

@@ -229,14 +229,19 @@ public Builder setEnableRequestSdrToneMapping(boolean enableRequestSdrToneMappin
     }
 
     /**
-     * Sets whether to attempt to process any input video stream as a high dynamic range (HDR)
-     * signal.
+     * Sets whether to allow processing high dynamic range (HDR) input video streams as HDR.
      *
      * <p>This method is experimental, and will be renamed or removed in a future release. The HDR
-     * editing feature is under development and is intended for developing/testing HDR processing
-     * and encoding support. HDR editing can't be enabled at the same time as {@linkplain
+     * editing feature is under development and is intended for developing/testing HDR support. HDR
+     * editing can't be enabled at the same time as {@linkplain
      * #setEnableRequestSdrToneMapping(boolean) SDR tone-mapping}.
      *
+     * <p>With this flag enabled, HDR streams will correctly edit in HDR, convert via tone-mapping
+     * to SDR, or throw an error, based on the device's HDR support. Without both this flag and
+     * {@linkplain #setEnableRequestSdrToneMapping(boolean) SDR tone-mapping} as false, HDR streams
+     * will be incorrectly interpreted as SDR streams, with no conversion. SDR streams will be
+     * interpreted the same way regardless of this flag's state.
+     *
      * @param enableHdrEditing Whether to attempt to process any input video stream as a high
      *     dynamic range (HDR) signal.
      * @return This builder.