Add newline to Dockerfile

Author: chainchad

plugins/chainlink.prebuilt.Dockerfile

@@ -14,4 +14,4 @@ ARG LOCAL_LIB_DIR=./lib
 # Copy/override any additional shared libraries.
 COPY ${LOCAL_LIB_DIR} /usr/lib/
 # Copy/override plugins.
-COPY ${LOCAL_PLUGIN_DIR} /usr/local/bin
+COPY ${LOCAL_PLUGIN_DIR} /usr/local/bin