[BUGFIX] Fix typo in RTE contentsCss example

Releases: master, 11.5, 10.4
Resolves: #96040
Change-Id: Idc83eedacc1ab00f761e179e394e173a071b6b0d
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/72130
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>

typo3/sysext/rte_ckeditor/Documentation/Configuration/Reference.rst

@@ -71,7 +71,7 @@ editor.config
 
    Example::
 
-      editor.config.contentCss: "EXT:rte_ckeditor/Resources/Public/Css/contents.css"
+      editor.config.contentsCss: "EXT:rte_ckeditor/Resources/Public/Css/contents.css"
 
    This is the default, as defined in `EXT:rte_ckeditor/Configuration/RTE/Editor/Base.yaml
    <https://github.com/typo3/typo3/blob/master/typo3/sysext/rte_ckeditor/Configuration/RTE/Editor/Base.yaml>`__.