CLEANUP: Tweak Dockerfile a little and add comments to make it clearer.

Dockerfile

@@ -1,11 +1,27 @@
+# Build stage - Use a full build environment to create a static binary
 FROM golang:1.11
-WORKDIR /go/src/github.com/OpenBazaar/openbazaar-go
-COPY . .
-RUN go build --ldflags '-extldflags "-static"' -o /opt/openbazaard .
+COPY . /go/src/github.com/OpenBazaar/openbazaar-go
+RUN go build --ldflags '-extldflags "-static"' -o /opt/openbazaard /go/src/github.com/OpenBazaar/openbazaar-go
 
+# Final state - Create image containing nothing but the openbazaard binary and
+# some base settings
 FROM openbazaar/base:v1.0.0
+
+# Document ports in use
+#   4002 - HTTP(s) API
+#   4001 - libp2p/IPFS TCP port
+#   9005 - libp2p/IPFS websocket port
 EXPOSE 4001 4002 9005
-ENTRYPOINT ["/opt/openbazaard"]
+
+# Define a volume to perist data to. This data contains all the important
+# elements defining a peer so it must be durable as long as the identity exists
 VOLUME /var/lib/openbazaar
+
+# Tell the image what to execute by default. We start a mainnet OB server
+# that uses the defined volume for node data
+ENTRYPOINT ["/opt/openbazaard"]
 CMD ["start", "-d", "/var/lib/openbazaar"]
+
+# Copy the compiled binary into this image. It's COPY'd last since the rest of
+# this stage rarely changes while the binary changes every commit
 COPY --from=0 /opt/openbazaard /opt/openbazaard