Add learn more p-link to media router dialog

Bug: 275073444
Test: Manually using media router sample app.
Change-Id: I3d4454a26f6321495980a4648c66b7f25e8fef02
diff --git a/mediarouter/mediarouter/src/main/res/values/strings.xml b/mediarouter/mediarouter/src/main/res/values/strings.xml
index 8b54407..40d73e1 100644
--- a/mediarouter/mediarouter/src/main/res/values/strings.xml
+++ b/mediarouter/mediarouter/src/main/res/values/strings.xml
@@ -99,10 +99,10 @@
     No devices available
 
     
-    Unable to find devices, make sure your device and the Cast device are on the same Wi-Fi network and try again.
+    Learn more about how you can cast your content to other devices.
 
     
-    Make sure your device and the Cast device are on the same Wi-Fi network.
+    Make sure your device and the Cast device are on the same Wi-Fi network. \n\nLearn more
 
     
     Done