player: Add media information get_type() functions to docs
player: Add media information get_type() functions to docs

https://github.com/sdroege/gst-player/pull/25

JimmyOhn/gst-player,JimmyOhn/gst-player,codomania/gst-player,sdroege/gst-player,amorenoc/gst-player,shakin/gst-player,sdroege/gst-player,sdroege/gst-player,amorenoc/gst-player,jabiers/gst-player,amorenoc/gst-player,codomania/gst-player,amorenoc/gst-player,JimmyOhn/gst-player,justinjoy/gst-player,codomania/gst-player,shakin/gst-player,amorenoc/gst-player,jabiers/gst-player,JimmyOhn/gst-player,JimmyOhn/gst-player,justinjoy/gst-player,justinjoy/gst-player,guiseco/gst-player,jabiers/gst-player,guiseco/gst-player,shakin/gst-player,sdroege/gst-player,codomania/gst-player,codomania/gst-player,guiseco/gst-player,sdroege/gst-player