instruction command was not documented in right format.

Instructions for a Multiple Server Swift Installation (Ubuntu) doc
for creating /var/run/swift and changing owner command were not
using the right format. Missing two colons.

Change-Id: Ie23007a0da498373fbfb137c7edb3d80813c6ba5
Fixes: bug #1158310
(cherry picked from commit c1dfe891e76b2b8ebb99efb71cf61aa81110348e)
Merge "instruction command was not documented in right format." into milestone-proposed