Add tracpro to path before building docs

So that we can import the version.

docs/source/conf.py

@@ -12,10 +12,15 @@
 # All configuration values have a default; values that are commented out
 # serve to show the default.
 
+import os
+import sys
+
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
-# sys.path.insert(0, os.path.abspath('.'))
+project_root = os.path.abspath(os.path.join(
+    os.path.dirname(__file__), os.pardir, os.pardir))
+sys.path.insert(0, project_root)
 
 # -- General configuration ------------------------------------------------