Rename pre-build to pre_build

hooks/pre_build

@@ -0,0 +1,8 @@
+#!/bin/bash
+
+# Source: https://github.com/ckulka/docker-multi-arch-example/blob/master/hooks/pre_build
+# Used to setup QEMU to build arm images on amd64 processors.
+
+# Register qemu-*-static for all supported processors except the
+# current one, but also remove all registered binfmt_misc before
+docker run --rm --privileged multiarch/qemu-user-static:register --reset