added cron to nginx image

nginx/Dockerfile-fpm-nginx

 FROM dmstr/php-yii2:latest
 
 # Install Forego
-# TODO: use RUN curl ... for better build caching
-ADD https://github.com/jwilder/forego/releases/download/v0.16.1/forego /usr/local/bin/forego
+RUN curl -L -o /usr/local/bin/forego https://github.com/jwilder/forego/releases/download/v0.16.1/forego
 RUN chmod u+x /usr/local/bin/forego
 
 # Install nginx
 RUN apt-get update \
  && apt-get install -y --force-yes \
             nginx-full \
+            cron \
         --no-install-recommends && \
     apt-get clean && \
     rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
@@ -18,7 +18,8 @@ COPY image-files/ /
 
 # forward request and error logs to docker log collector
 RUN ln -sf /dev/stdout /var/log/nginx/access.log \
- && ln -sf /dev/stderr /var/log/nginx/error.log
+ && ln -sf /dev/stderr /var/log/nginx/error.log \
+ && ln -sf /usr/sbin/cron /usr/sbin/crond
 
 CMD ["forego", "start", "-r", "-f", "/root/Procfile"]
 

nginx/image-files/root/Procfile

 nginx: nginx -g 'daemon off;'
 phpfpm: docker-run.sh
+cron: crond -f
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