docs: Correct Ubuntu installation instructions

Now should work with 18.04

Change-Id: I272c76ea93e1e075f5e162f868a859f207e2804e
diff --git a/docs/source/conf.py b/docs/source/conf.py
index 153ffed..8bdfd9f 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -30,7 +30,7 @@
     'sphinx.ext.mathjax',
     'sphinxcontrib.doxylink',
     'sphinxcontrib.aafig',
-    # 'sphinxcontrib.googleanalytics',
+    'sphinxcontrib.googleanalytics',
     'sphinxcontrib.bibtex',
     'redmine_issue'
 ]