Add swarm guide to /docs (#1513)

* docs: add swarm-guide

* readthedocs build configuration file

docs/swarm-guide/Dockerfile

@@ -0,0 +1,9 @@
+FROM python:3.7.1
+
+RUN pip install \
+    Sphinx==1.8.2 \
+    sphinx-rtd-theme==0.4.2 \
+    sphinx-tabs==1.1.10
+
+RUN mkdir -p /src
+WORKDIR /src