buildbucket.config: fix typo for options

CL 559740 tried to hide the retry builds button, but failed, likely
because the 'option' header is supposed to be spelled 'options'. Fix
that now.

Change-Id: I71f5f446a294768df60a88eecc3cb1a18bedb723
Reviewed-on: https://go-review.googlesource.com/c/All-Projects/+/560195
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

buildbucket.config

diff --git a/buildbucket.config b/buildbucket.config
index 20c6f8f..1179f24 100644
--- a/buildbucket.config
+++ b/buildbucket.config
@@ -4,5 +4,5 @@
 
 [bucket "luci.golang.try"]
 
-[option]
+[options]
 	hide-retry-button = true