Update Docker Build for Documentation

Simplify the docker script and calls to the doceker process in the
script. Remove separating of `Dockerfile` to a subdir.

tools/docker/build-documentation.sh

@@ -0,0 +1,19 @@
+#/bin/bash
+
+# checks for correct installation
+if [ ! $(docker -v | grep -c -w version) -eq 1 ]; then
+	echo "docker not found."
+	exit 1
+fi
+if [ ! $(groups | grep -c -w docker) -eq 1 ]; then
+	echo "add current user $(whoami) to docker group!"
+	exit 1
+fi
+
+# build containter
+echo "start building Docker container 'mied-documentation'"
+docker build -t mies-documentation .
+# run doxygen and print version string
+echo "Doxygen version" $(docker run --rm mies-documentation doxygen -v)
+# execute build script
+docker run --rm -v $(git rev-parse --show-toplevel):/opt/mies mies-documentation /bin/bash /opt/mies/tools/build-documentation.sh