feat(proposal): add reference for context

pub/proposal/proposal.tex

@@ -67,7 +67,7 @@ sure that they work consistently~\cite{manifesto}, which tests
 that the procedures in the checklist are concise, achieves the goal
 of the critical procedure, and will not take too long to complete.
 These checklists are also carried out in high workload environments,
-and this workload is elevated if an emergency were to occur.
+and this workload is elevated if an emergency were to occur.~\cite{caa-emergency}
 
 \subsubsection*{Problem}
 %\begin{itemize}

pub/proposal/references.bib

@@ -66,3 +66,12 @@
             },
 }
 
+@manual{caa-emergency,
+  author = {Civil Aviation Authority},
+  title = {Aircraft Emergencies: Considerations for air traffic controllers},
+  number = {CAP745},
+  year = {2005},
+  month = {3},
+  url = {https://www.caa.co.uk/cap745},
+}
+