Correct tagged version docs build

A variable reassignment in conf.py caused errors when we try to build
release versions of docs.  Correct that by swapping the order of use
and assignment.

Change-Id: Idf0116177cdebf9edb248fe8ca16c0bbcc6d8150

doc/source/conf.py

@@ -69,8 +69,8 @@ pygments_style = 'sphinx'
 html_theme = "sphinx_rtd_theme"
 
 if version.is_release:
-    version = version.release_string
     current_version = version.release_string
+    version = version.release_string
     versions = [('latest', f'{doc_root}/')]
 else:
     # Uncomment this if we want to use the in-development version