[TASK] Add end of life hint

Releases: 11.5

Documentation/Includes.rst.txt

@@ -1,4 +1,13 @@
-.. More information about this file:
+..  attention::
+    TYPO3 v11 has reached end-of-life as of October 15th 2024 and
+    is no longer being maintained. Use the version switcher on the top left of
+    this page to select documentation for a supported version of TYPO3.
+
+    Need more time before upgrading?
+    You can purchase Extended Long Term Support (ELTS) for TYPO3 v11 here:
+    `TYPO3 ELTS <https://typo3.com/services/extended-support-elts>`__.
+
+.. More information about this file:
    https://docs.typo3.org/m/typo3/docs-how-to-document/main/en-us/GeneralConventions/FileStructure.html#includes-rst-txt
 
 .. ----------