set current branch of apm-agent-python to 1.x (#274)

set current branch of apm-agent-python to "1.x", add "2.x" and "master"

Author: beniwohli

conf.yaml

@@ -773,8 +773,8 @@ contents:
               -
                 title:      APM Python Agent
                 prefix:     python
-                current:    master
-                branches:   [ master ]
+                current:    1.x
+                branches:   [ master, 2.x, 1.x ]
                 index:      docs/index.asciidoc
                 tags:       APM Python Agent/Reference
                 chunk:      1