Add missing "ps" requirement to PACKAGERS.md

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)

docs/sources/installation/binaries.md

@@ -25,6 +25,7 @@ runtime:
 
 -   iptables version 1.4 or later
 -   Git version 1.7 or later
+-   procps (or similar provider of a "ps" executable)
 -   XZ Utils 4.9 or later
 -   a [properly
     mounted](https://github.com/tianon/cgroupfs-mount/blob/master/cgroupfs-mount)

docs/sources/installation/binaries.rst

@@ -28,6 +28,7 @@ To run properly, docker needs the following software to be installed at runtime:
 
 - iptables version 1.4 or later
 - Git version 1.7 or later
+- procps (or similar provider of a "ps" executable)
 - XZ Utils 4.9 or later
 - a `properly mounted
   <https://github.com/tianon/cgroupfs-mount/blob/master/cgroupfs-mount>`_

hack/PACKAGERS.md

@@ -265,6 +265,7 @@ To function properly, the Docker daemon needs the following software to be
 installed and available at runtime:
 
 * iptables version 1.4 or later
+* procps (or similar provider of a "ps" executable)
 * XZ Utils version 4.9 or later
 * a [properly
   mounted](https://github.com/tianon/cgroupfs-mount/blob/master/cgroupfs-mount)