The XSL license was standardized by SPDX as DocBook-XML.
Copy the license file to the new name and use it in
docbook-xsl-stylesheets.
License-Update: use new DocBook-XML SPDX ID, copy text from existing XSL
(From OE-Core rev: e172e27e19fc09160cfee2a29af8e8c5c2426c9c)
Signed-off-by: Bastian Germann <bage@debian.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
