[DMDB] Finish first version of summary

semester4/dmdb/glossary/defs.tex

@@ -2,3 +2,10 @@
     name={superkey},
     description={See Section \ref{sec:functional-dependency}}
 }
+\newglossaryentry{quorum}{
+    name={quorum},
+    description={
+            See \href{https://en.wikipedia.org/wiki/Quorum_(distributed_computing)}{this Wikipedia article}.
+            TL;DR: It is a synchronization system for distributed computing.
+        }
+}