Add link to command-interface library

Author: fraya

docs/source/index.rst

@@ -27,4 +27,5 @@ Packages
 * `base64 <https://dylan-lang.github.io/base64/>`_
 * `binary-data <https://dylan-lang.github.io/binary-data/>`_
 * `collection-extensions <https://dylan-lang.github.io/collection-extensions/>`_
+* `command-interface <http://dylan-lang.github.io/command-interface/>`_
 * `testworks <https://dylan-lang.github.io/testworks/>`_