README: remove requirement for CHANGELOG entry

As indicated elsewhere in the README, the standalone CHANGELOG file was
removed in 2010.  Drop the instructions for creating patches on creating
a standalone CHANGELOG entry.

Signed-off-by: Karl Palsson <karlp@tweak.net.au>
diff --git a/README b/README
index 8cfa92f..0f95785 100644
--- a/README
+++ b/README
@@ -4734,8 +4734,6 @@
 * For new features: a description of the feature and your
   implementation.
 
-* A CHANGELOG entry as plaintext (separate from the patch)
-
 * For major contributions, add a MAINTAINERS file with your
   information and associated file and directory references.