install: update arch instructions

content/install.rst

@@ -116,10 +116,8 @@ documentation will be installed locally in the directory
 Arch Linux
 ==========
 
-*(This section still targets Python 2 and needs to be updated for Python 3.)*
-
-‘Arch install scripts for Kwant
-<https://aur.archlinux.org/packages/python2-kwant/>‘_ are kindly provided by
+`Arch install scripts for Kwant
+<https://aur.archlinux.org/packages/python-kwant/>`_ are kindly provided by
 Jörg Behrmann (formerly by Max Schlemmer).  To install, follow the `Arch User
 Repository installation instructions
 <https://wiki.archlinux.org/index.php/Arch_User_Repository#Installing_packages>`_.