Merge pull request #2 from rodolfo42/patch-2

clarify .npmrc mount

drun

@@ -8,7 +8,7 @@ usage_noexit() {
   echo >&2 '  -h           Help'
   echo >&2 '  -k           Keep container after run (i.e. does not user docker run --rm option)'
   echo >&2 '  -x           Enables bash xtrace so that exact `docker run` command is displayed'
-  echo >&2 '  -N           Uses node:AUTO image, where AUTO is detected from a local package.json if any'
+  echo >&2 '  -N           Uses node:AUTO image, where AUTO is detected from a local package.json if any (also mounts .npmrc, if present)'
   echo >&2 '  -P           Mounts your ~/.npm/ into the container (Only useful with node, obviously)'
   echo >&2 '  -v VOL_SPEC  Adds a --volume option to `docker run`'
   echo >&2 '  -e ENV_SPEC  Adds a --env option to `docker run`'