Add label to link GH package to a repository

Signed-off-by: Riddhesh Sanghvi <riddhesh237@gmail.com>

Author: mrrobot47

Dockerfile

@@ -5,6 +5,7 @@ LABEL "com.github.actions.icon"="check-circle"
 LABEL "com.github.actions.color"="green"
 LABEL "com.github.actions.name"="PHPCS Code Review"
 LABEL "com.github.actions.description"="This will run phpcs on PRs"
+LABEL "org.opencontainers.image.source"="https://github.com/rtCamp/action-phpcs-code-review"
 
 RUN echo "tzdata tzdata/Areas select Asia" | debconf-set-selections && \
 echo "tzdata tzdata/Zones/Asia select Kolkata" | debconf-set-selections