Fix typo in Dockerfile to correct jar file copy command

Author: mkjsix

Diff for: core/Dockerfile

@@ -20,7 +20,7 @@ RUN apt-get update && \
 WORKDIR /opt/restheart
 
 # Copy the executable jar and the required libraries
-COPY target/restheart.jar ./restheart.jarq
+COPY target/restheart.jar ./restheart.jar
 COPY target/lib/*.jar lib/
 COPY target/plugins/*.jar plugins/
 COPY target/plugins/lib/*.jar plugins/lib/