Represent 'tie number' in foldout in singular form

Signed-off-by: Anth0rx <anthorx@keemail.me>

fold_back.tex

@@ -60,7 +60,7 @@
   \glsdesc{action}
   \par
   \vspace{1em}
-  \subsubsection{\Glsfmtlongpl{tn}}
+  \subsubsection{\Glsfmtlong{tn}}
   \glsdesc{tn}.
 }