fix rm -rf path

Dockerfile

@@ -12,11 +12,11 @@ RUN apt-get update -qq && \
     apt-get install --yes signal-desktop && \
     apt-get -qq --yes autoremove --purge && \
     apt-get -qq --yes clean all && \
-    rm -rf "/usr/share/doc/*" \
-       "/var/cache/*" \
-       "/var/lib/apt/lists/*" \
-       "/usr/src/*" \
+    rm -rf "/usr/share/doc/"* \
+       "/var/cache/"* \
+       "/var/lib/apt/lists/"* \
+       "/usr/src/"* \
        "/var/log/"{apt/*,dpkg.log} \
-       "/tmp/*"
+       "/tmp/"*
 
 CMD [ "signal-desktop" ]