Evaluate usage of "resource" protocol

JavaFX Media has "resource" protocol listed under supported protocols, however it is not clear if we need to support it. As part of this task we need to evaluate usage of this protocol and document it or remove it.

Also, "jrt" protocol is missing form JavaDoc. We need to document it as well.

https://github.com/openjdk/jfx/blob/master/modules/javafx.media/src/main/java/com/sun/media/jfxmediaimpl/platform/gstreamer/GSTPlatform.java#L66