Add more explaination for TS:data SiteLanguage:locale #1409 (#1413)

* Add more explaination for TS:data SiteLanguage:locale #1409

* Add description for locale itself

(cherry picked from commit 26909ce)

Author: froemken

Documentation/Functions/Data.rst

@@ -949,14 +949,25 @@ siteLanguage
 
     :typoscript:`locale`
         ..  versionchanged:: 12.3
-            Several subkeys are available:
-
-            *  :typoscript:`languageCode`: this contains the two-letter language code (previously :typoscript:`siteLanguage:twoLetterIsoCode`)
-            *  :typoscript:`countryCode`: contains the uppercase country code part of the locale
-            *  :typoscript:`full`: contains the entire locale (also the default if no subkey is specified)
-
-        The locale, like `de_CH` or `en_GB` (also available from the subkey :typoscript:`locale.full`).
-        
+            The :typoscript:`locale` property in typoscript can be subdivided
+            into more specific details using subkeys separated by a colon `:`.
+            The subkeys `languageCode`, `countryCode`, and `full` allow access
+            to the individual components of the :typoscript:`locale` value. For
+            instance, a :typoscript:`locale` value of "en_US.UTF-8" can be
+            broken down into "en", "US", and for the `full` subkey, "en-US".
+
+            *   :typoscript:`languageCode`: this contains the two-letter
+                language code (previously
+                :typoscript:`siteLanguage:twoLetterIsoCode`)
+            *   :typoscript:`countryCode`: contains the uppercase country code
+                part of the locale
+            *   :typoscript:`full`: contains the entire locale (also the default
+                if no subkey is specified)
+
+        The :typoscript:`locale` property represents the language, country, and
+        character encoding settings for TYPO3. It is a composite value, such as
+        "en_US.UTF-8", which can be dissected into different components via
+        subkeys for more precise language and location specifications.
 
     :typoscript:`navigationTitle`
         The label to be used within language menus.