doc: remove duplicated section

README.md

@@ -707,36 +707,6 @@ final class SecondImplementation implements SomeInterface
 }
 ```
 
-### Modifiers
-
-Sometimes the source is not in the same format and/or organised in the same
-way as a value object. Modifiers can be used to change a source before the
-mapping occurs.
-
-#### Camel case keys
-
-This modifier recursively forces all keys to be in camelCase format.
-
-```php
-final class SomeClass
-{
-    public readonly string $someValue;
-}
-
-$source = new \CuyZ\Valinor\Mapper\Source\Modifier\CamelCaseKeys([
-    'some_value' => 'foo',
-    // …or…
-    'some-value' => 'foo',
-    // …or…
-    'some value' => 'foo',
-    // …will be replaced by `['someValue' => 'foo']`
-]);
-
-(new \CuyZ\Valinor\MapperBuilder())
-    ->mapper()
-    ->map(SomeClass::class, $source);
-```
-
 ## Handled types
 
 To prevent conflicts or duplication of the type annotations, this library tries