Added versionadded directive

Author: javiereguiluz

reference/constraints/Uuid.rst

@@ -138,6 +138,10 @@ The following PHP constants can also be used:
 
 All six versions are allowed by default.
 
+.. versionadded:: 5.2
+
+    The UUID 6 version support was introduced in Symfony 5.2.
+
 .. _`Universally unique identifier (UUID)`: https://en.wikipedia.org/wiki/Universally_unique_identifier
 .. _`RFC 4122`: https://tools.ietf.org/html/rfc4122
 .. _`UUID versions`: https://en.wikipedia.org/wiki/Universally_unique_identifier#Versions