Update README.md

Added the sample of external using. Cleanup

Author: urpylka

README.md

@@ -1,42 +1,76 @@
+# qemu-register
+
 [![Build Status](https://circleci.com/gh/hypriot/qemu-register.svg?style=svg)](https://circleci.com/gh/hypriot/qemu-register)
 
-### Build Docker image
-```
-./build.sh
+qemu-register – is the docker-image providing `qemu-static` binaries for your cross-platform projects.
+
+A simple way to register `qemu` usermode emulation binaries for your kernel:
+
+```docker
+FROM hypriot/qemu-register as qemu
+
+# Fetching your base image (you can select another one)
+FROM alpine
+
+# Coping compiled binaries to your image
+COPY --from=qemu /qemu-aarch64 /qemu-arm
+COPY --from=qemu /qemu-aarch64 /qemu-aarch64
+COPY --from=qemu /qemu-aarch64 /qemu-ppc64le
+COPY --from=qemu /qemu-aarch64 /qemu-riscv64
+
+# Coping & executing script for registering qemu in the kernel
+COPY --from=qemu /register.sh /register.sh
+RUN /register.sh --reset
+
+# PUT HERE YOUR INSTRUCTIONS!!!
+
 ```
 
+## How this works
 
-### Check Qemu binaries and versions
+Starting with the Linux kernel 4.8, there's a mechanism in the kernel to load the interpreter specified in your `binfmt_misc` ahead of time (and make sure it stays in memory even if the interpreter file is deleted or moved). This is described in better detail in [this blog post by npmccallum](https://npmccallum.gitlab.io/post/foreign-architecture-docker/), [nmpccallum`s github](https://github.com/npmccallum/qemu-register) and in the [kernel binfmt_misc docs](https://www.kernel.org/doc/Documentation/admin-guide/binfmt-misc.rst).
+
+### Build Docker image
+
+If you wanna build your own qemu-register using next instruction:
+
+```bash
+git clone https://github.com/hypriot/qemu-register.git
+cd qemu-register
+docker build -t hypriot/qemu-register:local .
 ```
-docker run --rm hypriot/qemu-register sh -c 'ls -al /qemu*'
+
+### Check Qemu binaries and versions
+
+```bash
+$ docker run --rm hypriot/qemu-register sh -c 'ls -al /qemu*'
 -rwxr-xr-x    1 root     root       6192520 Apr 27 11:25 /qemu-aarch64
 -rwxr-xr-x    1 root     root       5606984 Apr 27 11:25 /qemu-arm
 -rwxr-xr-x    1 root     root       5987464 Apr 27 11:25 /qemu-ppc64le
 
-docker run --rm hypriot/qemu-register /qemu-arm --version
+$ docker run --rm hypriot/qemu-register /qemu-arm --version
 qemu-arm version 4.2.0
 Copyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers
 
-docker run --rm hypriot/qemu-register /qemu-aarch64 --version
+$ docker run --rm hypriot/qemu-register /qemu-aarch64 --version
 qemu-aarch64 version 4.2.0
 Copyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers
 
-docker run --rm hypriot/qemu-register /qemu-ppc64le --version
+$ docker run --rm hypriot/qemu-register /qemu-ppc64le --version
 qemu-ppc64le version 4.2.0
 Copyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers
 
-docker run --rm hypriot/qemu-register /qemu-riscv64 --version
+$ docker run --rm hypriot/qemu-register /qemu-riscv64 --version
 qemu-riscv64 version 4.2.0
 Copyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers
 ```
 
-
 ### Run the resulting Docker image to register the Qemu interpreters
+
 ```
 docker run --rm --privileged hypriot/qemu-register
 ```
 
-
 ### Buy us a beer!
 
 This FLOSS software is funded by donations only. Please support us to maintain and further improve it!