feat(proposal): add checklist manifesto source filler

pub/proposal/proposal.tex

@@ -107,6 +107,10 @@
       which is the focus of this project and will provide guidance 
       on how the tests should be carried out. \\
 
+    \multirow{2}{*}{\parbox{8em}{The Checklist Manifesto~\cite{manifesto}}}
+    & \textbf{Description:} Filler \\
+    & \textbf{Reason:} Filler \\
+
     \bottomrule
 \end{tabularx}