[kmd] Improvements in MediaObject reference documentation
[kmd] Improvements in MediaObject reference documentation

Change-Id: I05db7cbf02569781d247019ddec4336b91afec9f

ESTOS/kms-core,ESTOS/kms-core,Kurento/kms-core,ESTOS/kms-core,Kurento/kms-core,Kurento/kms-core,ESTOS/kms-core,Kurento/kms-core