core: add limit of 20 to group recursion

closes #3116

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

website/docs/releases/v2022.7.md

@@ -9,6 +9,11 @@ slug: "2022.7"
 
     Instead, create an OAuth Source with the certificate configured as JWKS Data, and enable the source in the provider.
 
+-   Maximum Limit of group recursion
+
+    In earlier versions, cyclic group relations can lead to a deadlock when one of groups in the relationship are bound to an application/flow/etc.
+    This is now limited to 20 levels of recursion.
+
 ## New features
 
 -   User paths

website/docs/user-group/group.md

@@ -8,6 +8,8 @@ Groups can be children of another group. Members of children groups are effectiv
 
 When you bind a group to an application or flow, any members of any child group of the selected group will have access.
 
+Recursion is limited to 20 levels to prevent deadlocks.
+
 ## Attributes
 
 Attributes of groups are recursively merged, for all groups the user is a _direct_ member of.