change format example to read better when rendered with full_messages

The capital O was awkward and the validation wouldn't read "right" to the user.

1 files changed, 1 insertions, 1 deletions

diff --git a/guides/source/active_record_validations.md b/guides/source/active_record_validations.md
index 621d2222ff..f10f0254e5 100644
--- a/guides/source/active_record_validations.md
+++ b/guides/source/active_record_validations.md
@@ -357,7 +357,7 @@ given regular expression, which is specified using the `:with` option.
 ```ruby
 class Product < ActiveRecord::Base
   validates :legacy_code, format: { with: /\A[a-zA-Z]+\z/,
-    message: "Only letters allowed" }
+    message: "only allows letters" }
 end
 ```