docs: replace With with with in title

Author: kenjis

user_guide_src/source/libraries/validation.rst

@@ -434,7 +434,7 @@ This can also be used to create more dynamic rules at runtime, as long as you ta
 keys passed in don't conflict with your form data.
 
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-Working With Errors
+Working with Errors
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 The Validation library provides several methods to help you set error messages, provide