env: Drop the unncessary protocol mention in autoload

Drop this text at the end since it already mentions bootp and dhcp.

Signed-off-by: Simon Glass <sjg@chromium.org>
Suggested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/doc/usage/environment.rst b/doc/usage/environment.rst
index 4b228c1..80550fc 100644
--- a/doc/usage/environment.rst
+++ b/doc/usage/environment.rst
@@ -170,7 +170,7 @@
     if set to "no" (any string beginning with 'n'),
     "bootp" and "dhcp" will just load perform a lookup of the
     configuration from the BOOTP server, but not try to
-    load any image using TFTP or DHCP.
+    load any image.
 
 autostart
     if set to "yes", an image loaded using the "bootp", "dhcp",