Merge branch '6.4' into 7.0

* 6.4:
  [FrameworkBundle] Add note for `prefix_seed` about container compilation

Author: OskarStark

reference/configuration/framework.rst

@@ -3189,6 +3189,12 @@ It's also useful when using `blue/green deployment`_ strategies and more
 generally, when you need to abstract out the actual deployment directory (for
 example, when warming caches offline).
 
+.. note::
+
+    The ``prefix_seed`` option is used at compile time. This means
+    that any change made to this value after container's compilation
+    will have no effect.
+
 .. _reference-lock:
 
 lock