ipam/allocator: Fix typos in error message

Signed-off-by: Euan Harris <euan.harris@docker.com>

libnetwork/ipam/allocator.go

@@ -389,7 +389,7 @@ func (a *Allocator) getPredefinedPool(as string, ipV6 bool) (*net.IPNet, error)
 	}
 
 	if as != localAddressSpace && as != globalAddressSpace {
-		return nil, types.NotImplementedErrorf("no default pool availbale for non-default addresss spaces")
+		return nil, types.NotImplementedErrorf("no default pool available for non-default address spaces")
 	}
 
 	aSpace, err := a.getAddrSpace(as)