Sort installation snippets by OS name alphabetically

app/views/docs/installation.html.md

@@ -11,20 +11,6 @@ be installed with pip (Python 3 required):
 
 ## Native packages
 
-### OS X
-
-Homebrew:
-
-<%= render 'install_homebrew' %>
-
-MacPorts:
-
-    sudo port selfupdate && sudo port install asciinema
-
-Nix:
-
-    nix-env -i go1.4-asciinema
-
 ### Arch Linux
 
     yaourt -S asciinema
@@ -61,6 +47,20 @@ Packages:
 
     nix-env -i go1.4-asciinema
 
+### OS X
+
+Homebrew:
+
+<%= render 'install_homebrew' %>
+
+MacPorts:
+
+    sudo port selfupdate && sudo port install asciinema
+
+Nix:
+
+    nix-env -i go1.4-asciinema
+
 ### Ubuntu
 
     sudo apt-add-repository ppa:zanchey/asciinema