update README.md, switch user in Dockerfile(drop privileges), remove .gitlab-ci.yml

Dockerfile

@@ -2,9 +2,9 @@ FROM node:lts-alpine3.12
 RUN mkdir /data
 COPY ./ /data
 WORKDIR /data
-RUN ls -lash
 RUN yarn install --production
 RUN adduser --disabled-password --gecos "" slowdowner
 RUN chown slowdowner:slowdowner /data
+USER slowdowner
 CMD yarn run start
 EXPOSE 8080