Update Dockerfile

added nano and bash for easier editing of "settings.txt" and direct use of the internal synology terminal button with bash instead of sh.

Dockerfile

@@ -3,7 +3,7 @@ FROM python:alpine
 WORKDIR /usr/src/app
 
 # install dependencies for domain-connect-dyndns
-RUN apk add -U --no-cache gcc build-base linux-headers ca-certificates python3 python3-dev libffi-dev libressl-dev nano
+RUN apk add -U --no-cache gcc build-base linux-headers ca-certificates python3 python3-dev libffi-dev libressl-dev nano bash
 
 RUN pip install domain-connect-dyndns