Update changelog.md

FreeApophis · Ruben Schmidmeister · web-flow · commit 58bb2dbcf4ab · 2020-06-09T15:43:50.000+02:00
Co-authored-by: Ruben Schmidmeister &lt;ruben.schmidmeister@messerli.ch&gt;
diff --git a/changelog.md b/changelog.md
@@ -13,5 +13,5 @@
 * Match of `Result` Monad accepts actions
 * Add `FirstOrNone`, `LastOrNone` and `SingleOrNone` extension functions
 
-## unreleased
+## Unreleased
 * Added overload for AndThen which flattens the Option
