From a81bff9349db99c1be6e69d5c196976dc3693c46 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Wed, 22 Jun 2016 07:01:43 -0700
Subject: [PATCH] Update documentation build instructions

---
 doc/usage.rst | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/doc/usage.rst b/doc/usage.rst
index 27d96ede..30870c6d 100644
--- a/doc/usage.rst
+++ b/doc/usage.rst
@@ -62,7 +62,11 @@ system:
 
 * `Python <https://www.python.org/>`_ with pip and virtualenv
 * `Doxygen <http://www.stack.nl/~dimitri/doxygen/>`_
-* `Less <http://lesscss.org/>`_ with less-plugin-clean-css
+* `Less <http://lesscss.org/>`_ with ``less-plugin-clean-css``.
+  Ubuntu doesn't package the ``clean-css`` plugin so you should use ``npm``
+  instead of ``apt`` to install both ``less`` and the plugin::
+
+    sudo npm install -g less less-plugin-clean-css.
 
 First generate makefiles or project files using CMake as described in
 the previous section. Then compile the ``doc`` target/project, for example::