Improve typography

wiki/src/contribute/working_together/code_of_conduct.mdwn

@@ -2,7 +2,7 @@
 
 Like the technical community as a whole, the Tails team and community
 is made up of a mixture of people from all over the world, working on
-every aspect of the mission -- including mentorship, teaching, and
+every aspect of the mission — including mentorship, teaching, and
 connecting people.
 
 Diversity is one of our huge strengths, but it can also lead to
@@ -12,7 +12,7 @@ participating within this community and project. These rules apply
 equally to founders, mentors and those seeking help and guidance.
 
 This isn’t an exhaustive list of things that you can’t do. Rather,
-take it in the spirit in which it’s intended -- a guide to make it
+take it in the spirit in which it’s intended — a guide to make it
 easier to enrich all of us and the technical communities in which
 we participate.