Bug 30721: Markup error in detail page's component parts tab

Bug 30721: Markup error in detail page's component parts tab

This patch adds a missing </div> to the bibliographic detail
page template in the section for showing component parts.
Some comments are added to clarify the markup structure.

To test you should have a record in your catalog with component
parts. Bug 11175 provides one you can import if necessary:
https://bugs.koha-community.org/bugzilla3/attachment.cgi?id=78023

To see the error, go to the staff interface, locate the record
in question and view the detail page. Under the Components tag,
scroll to the bottom. You will see content from "later" tabs at
the bottom, e.g. "There is no order for this bibliographic record"
or "No images have been uploaded for this bibliograhpic record yet."

Apply the patch and reload the page. The tabs should still look
correct, and now the tab content should be correctly isolated.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>