Bug 10052 Followup for edithelp.tt and help-top.inc

Bug 10052 Followup for edithelp.tt and help-top.inc

A grep on the stylesheet names revealed that similar code was used in those
template files.
This patch moves the code from doc-head-close.inc to a new include file.
Now, doc-head-close and the help templates refer to that one file.

Test plan:
If you tested the preceding two patches, now you only need to:
1) Check included css via page source in browser from staff main page.
2) Check it also from some other location.
3) Check again from Help: e.g. /cgi-bin/koha/help.pl
4) Check again from Edit Help: /cgi-bin/koha/edithelp.pl

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Template only, no string changes.
Tested according to test plan.
Signed-off-by: Galen Charlton <gmc@esilibrary.com>