Document need for ldconfig on Linux
Document need for ldconfig on Linux

On Linux, ldconfig needs to be run after installing shared libraries
to system paths (typically /usr/local/lib, /usr/lib and /lib).
Document this.

Fixes #586

git-svn-id: 7d4b18ab7d176792635d6a7a77dd8cbbea8e8daa@4420 d4fa192b-c00b-0410-8231-f00ffab90ce4

wikimedia/operations-debs-varnish,CartoDB/Varnish-Cache,wikimedia/operations-debs-varnish,ssm/pkg-varnish,wikimedia/operations-debs-varnish,wikimedia/operations-debs-varnish,ssm/pkg-varnish,ssm/pkg-varnish,ssm/pkg-varnish,ssm/pkg-varnish,CartoDB/Varnish-Cache,wikimedia/operations-debs-varnish,CartoDB/Varnish-Cache