Image now contains nRF Connect SDK

[coderbyheart]

I have change the Docker file so that it now includes the clone of the nRF Connect SDK used to install the required dependencies. This simplifies building applications from the SDK as well as out-of tree.

Below is the main change:

- docker run --rm -v ${PWD}:/workdir/project nordicplayground/nrfconnect-sdk:main /bin/bash -c 'cd firmware && west init -l && west update --narrow -o=--depth=1 && west build -p always -b nrf9160dk_nrf9160_ns'
+ docker run --rm -v ${PWD}:/workdir/project nordicplayground/nrfconnect-sdk:main west build -p always -b nrf9160dk_nrf9160_ns --build-dir /workdir/project/build

Using the west argument --build-dir allows to specify the output folder, which is a subfolder to the current working directory that is mounted to /workdir/project in the image.

Here is a real world example of how to migrate, and here is another.