Adding other spec-files to README

Change-Id: If6e28474a234dc1ca01d927a2a6c1f1a51f430c7
Reviewed-on: https://gerrit.libreoffice.org/36044Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>

sfx2/classification/README

@@ -2,3 +2,6 @@ Involved standards:
 
 - BAF is <https://www.tscp.org/wp-content/uploads/2013/08/TSCP_BAFv1.pdf>
 - BAILS is <http://www.tscp.org/wp-content/uploads/2013/08/TSCP_BAILSv1.pdf>
+- xAL is <http://www.oasis-open.org/committees/ciq>
+- xNL is <http://www.oasis-open.org/committees/ciq>
+- xlink is <http://www.oasis-open.org/committees/ciq>
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