Update docs/mediums/sortition.md, docs/mediums/secret_ballot.md, docs/mediums/board.md files

Deleted docs/mediums/boards.md

docs/mediums/secret_ballot.md

@@ -1,2 +1,7 @@
 # Secret ballot
 
+<!--
+Article 21.3 of the [Universal Declaration of Human Rights](https://www.un.org/en/universal-declaration-human-rights/index.html) regards secret ballots as a basic right by stating:
+
+> The will of the people shall be the basis of the authority of government; this will shall be expressed in periodic and genuine elections which shall be by universal and equal suffrage and shall be held by secret vote or by equivalent free voting procedures.
+-->

docs/mediums/sortition.md

@@ -37,3 +37,4 @@ In recent political systems, it is used most commonly for the formation of citiz
 
 * [Sortition Foundation](https://www.sortitionfoundation.org/)
 * "[Sortition](https://en.wikipedia.org/wiki/Sortition)" on Wikipedia
+* Van Reybrouck, David. "[Why Elections Are Bad for Democracy](https://www.theguardian.com/politics/2016/jun/29/why-elections-are-bad-for-democracy)." _The Guardian_. June 29, 2016.