Move all samples to the root dir

Signed-off-by: Anca Iordache <anca.iordache@docker.com>

nginx-flask-mongo/flask/Dockerfile

@@ -0,0 +1,7 @@
+FROM python:3.7
+
+WORKDIR /src
+COPY . .
+RUN pip install -r requirements.txt
+
+CMD ["./server.py"]