[gnome-builder] help: remove old transfers docs

[Christian Hergert <chergert src gnome org>]

commit 8a179d4d1f224b128556a1db597d7ff54bb9d34d
Author: Christian Hergert <chergert redhat com>
Date:   Tue Mar 12 17:04:08 2019 -0700

    help: remove old transfers docs

 doc/help/plugins/index.rst     |  1 -
 doc/help/plugins/transfers.rst | 58 ------------------------------------------
 2 files changed, 59 deletions(-)
---
diff --git a/doc/help/plugins/index.rst b/doc/help/plugins/index.rst
index c84f3d14b..3437de234 100644
--- a/doc/help/plugins/index.rst
+++ b/doc/help/plugins/index.rst
@@ -29,7 +29,6 @@ You may also chooser to implement extensions in C or Vala.
    session
    menus
    preferences
-   transfers
    workers
    vcs