Remove retry description

Dockerfile

@@ -25,9 +25,6 @@ RUN        bash /tmp/env-config.sh
 # and should only change as often as the dependencies
 # change. This layer should allow for final build times
 # to be limited only by the Calypso build speed.
-#
-# Sometimes "npm install" fails the first time when the
-# cache is empty, so we retry once if it failed
 COPY       ./package.json ./npm-shrinkwrap.json /calypso/
 RUN        true \
            && npm install --production \