Add copy software from stage comments. [skip ci].

Dockerfile

@@ -22,7 +22,9 @@ RUN apt-get update && \
 	procps \
 	wget
 
+# Copy softwares from stage image
 COPY --from=stage /artifacts /
+
 RUN mkdir -p /etc/ldap/sasl2 \
 	&& echo "mech_list: GSSAPI EXTERNAL" >> /etc/ldap/sasl2/slapd.conf \
 	&& mkdir -p /var/lib/ldap/accesslog \