docs: Add some packages for building the docs

Change-Id: I7af427ba6378ddd8480a153a65ec11c578bab12e
Signed-off-by: jdenisco <jdenisco@cisco.com>
diff --git a/docs/gettingstarted/writingdocs/buildingrst.rst b/docs/gettingstarted/writingdocs/buildingrst.rst
index 46830ca..474257d 100644
--- a/docs/gettingstarted/writingdocs/buildingrst.rst
+++ b/docs/gettingstarted/writingdocs/buildingrst.rst
@@ -20,6 +20,17 @@
    $ cd vpp
 
 
+Install the Necessary Packages
+===============================
+
+Before building the docs there are some packages that are needed. To install
+these packages on ubuntu execute the following.
+
+.. code-block:: console
+
+   $ sudo apt-get install python3-all python3-setuptools python3-pip
+
+ 
 Create a Virtual Environment using virtualenv
 ===============================================