iproute: `route()` docs updated: multipath support
iproute: `route()` docs updated: multipath support

Bug-Url: https://github.com/svinota/pyroute2/issues/171
little-dude/pyroute2,mtiny/pyroute2,little-dude/pyroute2,simudream/pyroute2,drzaeus77/pyroute2,vodik/pyroute2,drzaeus77/pyroute2,little-dude/pyroute2,tomislacker/python-iproute2,roolebo/pyroute2,simudream/pyroute2,mtiny/pyroute2,tomislacker/python-iproute2,vodik/pyroute2,roolebo/pyroute2