refactor: Update figure caption in introduction section

The figure caption in the introduction section has been updated to include a citation for the co-clustering illustration. This change improves the clarity and accuracy of the figure caption.

sections/introduction.tex

@@ -30,7 +30,7 @@ \section{Introduction}
         \caption{Co-clustering}
         \label{fig:cocluster}
     \end{subfigure}
-    \caption{An illustration of the differences between (a) Clustering and (b) Co-clustering.}
+    \caption{An illustration of the differences between (a) Clustering and (b) Co-clustering \cite{yan2017CoclusteringMultidimensionalBig}.}
     \label{fig:cocomparison}
 \end{figure}