update Dockerfile and nginx config

Dockerfile

@@ -1,3 +1,11 @@
-FROM nginx
+FROM nginx:alpine
+
+# set labels
+LABEL org.opencontainers.image.authors="kasper.fischer@rub.de"
+
+# copy nginx config files
+COPY nginx/nginx.conf /etc/nginx/nginx.conf
+COPY nginx/default.conf /etc/nginx/conf.d/default.conf
+
+# copy webpage content
 COPY www /usr/share/nginx/html
-COPY nginx.conf /etc/nginx/nginx.conf