Move tljh-config symlink to /usr/bin

Removes a lot of 'sudo -E' usage, and eventually should
let us get rid of the $PATH override for jupyterhub-admins,
which arguably is less secure than just dropping stuff into
/usr/bin

Also remove sudo -E from apt and mkdir calls. Not necessary.

docs/howto/content/add-data.rst

@@ -81,7 +81,7 @@ time. You can download it from your browser `at this link <https://swcarpentry.g
 
    .. code-block:: bash
 
-      sudo -E apt-get install unzip
+      sudo apt install unzip
 
 #. Finally, unzip the the file:
 

docs/howto/content/share-data.rst

@@ -37,7 +37,7 @@ steps:
 
    .. code-block:: bash
 
-      sudo -E mkdir -p /srv/data/my_shared_data_folder
+      sudo mkdir -p /srv/data/my_shared_data_folder
 
 #. **Download the data** into this folder. See :ref:`howto/content/add-data` for
    details on how to do this.