Remove document file needless for ruby core

This reverts commit 743a31d639d4c96827b1b17f59c829c1ec31abc3,
"[ruby/date] [DOC] Make document coverage 100%".  This file is only
for rdoc coverage in the date gem, and useless when the built-in Time
is documented.

1 files changed, 0 insertions, 3 deletions

diff --git a/doc/time.rb b/doc/time.rb
deleted file mode 100644
index 013c52a498..0000000000
--- a/doc/time.rb
+++ /dev/null
@@ -1,3 +0,0 @@
-# Built-in class
-class Time
-end