Add README for media samples

Author: calren

samples/media/README.md

@@ -0,0 +1,24 @@
+# Media Samples
+
+- [Ultra HDR to HDR video](ultrahdr/src/main/java/com/example/platform/media/ultrahdr/video/UltraHDRToHDRVideo.kt):
+  Demonstrates converting a series of UltraHDR images into a HDR video.
+- [Transformer Video Composition](video/src/main/java/com/example/platform/media/video/TransformerVideoComposition.kt):
+  Demonstrates concatenation of two video assets and an image using Media3 Transformer library.
+
+## License
+
+```
+Copyright 2024 The Android Open Source Project
+ 
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    https://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+```

samples/media/video/src/main/java/com/example/platform/media/video/TransformerVideoComposition.kt

@@ -55,8 +55,8 @@ import java.util.concurrent.TimeUnit
 @UnstableApi
 @Sample(
     name = "Video Composition using Media3 Transformer",
-    description = "This sample demonstrates concatenation of two video assets using Media3 " +
-            "Transformer library.",
+    description = "This sample demonstrates concatenation of two video assets and an image using" +
+            " Media3 Transformer library.",
     documentation = "https://developer.android.com/guide/topics/media/transformer",
     tags = ["Transformer"],
 )