add webm and ogv
add webm and ogv

gigago/grav,Vivalldi/grav,tomzx/blog.tomrochette.com,webuxr/iamrs,notklaatu/grav,stell/grav,joeyhenricks/a-broke-vegan,tomzx/blog.tomrochette.com,dimayakovlev/grav,tomzx/blog.tomrochette.com,userfrosting/learn,JamesPan/gravbox,tomzx/blog.tomrochette.com,userfrosting/learn,sylvestrelucia/grav,sylvestrelucia/grav,notklaatu/grav,JamesPan/gravbox,sylvestrelucia/grav,Sommerregen/grav,dimayakovlev/grav,ccardinaux/grav-test,userfrosting/learn,getgrav/grav,JamesPan/gravbox,getgrav/grav,sylvestrelucia/grav,userfrosting/learn,Vivalldi/grav,joeyhenricks/a-broke-vegan,shortsofia/testesitegrav.github.io,JamesPan/gravbox