minor change

Doc/DevelopmentPlan/DevelopmentPlan.tex

@@ -104,7 +104,7 @@ The demonstration will be done on both a Windows and a Linux system. On each mac
 	\item \textbf{Programming Language: }Python
 	\item \textbf{Graphical User Interface: }Pyglet
 	\item \textbf{Testing Tools: }Pytest
-	\item \textbf{Documentation Tool: }Doxygen
+	\item \textbf{Documentation Tools: }Doxygen
 	\item \textbf{Version Control: }Gitlab
 	\item \textbf{Other Tools: }Pyinstaller
 \end{itemize}