[DOCS] Fix formatting in Webp changelog

Releases: main
Resolves: #103507
Change-Id: I571d99521ffa1e36b9cb18cb1621132d70f6382b
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/83628
Reviewed-by: Chris Müller <typo3@krue.ml>
Reviewed-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: Chris Müller <typo3@krue.ml>
Tested-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: core-ci <typo3@b13.com>

typo3/sysext/core/Documentation/Changelog/13.0/Feature-88537-WebPImageFormatSupportForImageProcessing.rst

@@ -29,7 +29,7 @@ Impact
 ======
 
 By default, WebP images can now be generated, as TYPO3's configuration setting
-:php:`$GLOBALS['TYPO3_CONF_VARS']['GFX']['imagefile_ext'] is now extended with
+:php:`$GLOBALS['TYPO3_CONF_VARS']['GFX']['imagefile_ext']` is now extended with
 "webp".
 
 Integrators can now use the file extension `webp` in their Fluid template or