feat(proposal): add reaction time background source

pub/proposal/proposal.tex

@@ -174,6 +174,15 @@ the checklist.
     & \textbf{Reason:} Checklist designer from Boeing is interviewed
     where they go through the vital design choices to make them effective
     and how they gain pilots' trust to use checklists. \\
+
+    \multirow{2}{*}{\parbox{8em}{Intraindividual Variability in Basic Reaction Time Predicts Middle-Aged and Older Pilots’ Flight Simulator Performance~\cite{pilot-reaction}}}
+    & \textbf{Description:} Tested 236 pilots aged between 40-69 years old, 
+    to measure their reaction times and how they are affected 
+    by age. The tests were conducted by Stanford
+    University and MIRECC, and results have been peer reviewed. \\
+    & \textbf{Reason:} Gives insightful statistics into pilots 
+    reaction times and how they will affect the performance 
+    when carrying out procedures in checklists. \\
 \end{xltabular}
 
 % Aim (or hypothesis) and Objectives