[PicaPlume] Forgot && in Dockerfile

pica-plume/Dockerfile

@@ -12,7 +12,7 @@ ENV FIRSTLAUNCH_PATH=/firstlaunch/yeah
 RUN apt-get update && \
     # See https://github.com/dalibo/temboard/issues/211#issuecomment-342205157 to understand why
     mkdir -p /usr/share/man/man1 && \
-    mkdir -p /usr/share/man/man7 \
+    mkdir -p /usr/share/man/man7 && \
     apt-get install -y postgresql-client && \
     rm -rf /var/lib/apt/lists/*