Updated directory path from tutorial to tutorials

shared/tutorial-preamble.tex

@@ -154,7 +154,7 @@ openany, % A chapter may start on either a recto or verso page.
 \ifdefined\HCode
 \newcommand{\relurl}[2]{\href{#1}{\underline{#1}}}
 \else
-\newcommand{\relurl}[2]{\url{http://doc.nektar.info/tutorial/\nekver/#2/#1}}
+\newcommand{\relurl}[2]{\url{http://doc.nektar.info/tutorials/\nekver/#2/#1}}
 \fi
 \endlinechar=13\relax