Changed hash_merge to link for ANSIBLE_HASH_BEHAVIOUR (#45996)

* Changed hash_merge, which goes nowhere, to link for ANSIBLE_HASH_BEHAVIOUR
* Changed link as per bcoca suggestion

docs/docsite/rst/user_guide/intro_inventory.rst

@@ -304,7 +304,7 @@ is an excellent way to track changes to your inventory and host variables.
 How Variables Are Merged
 ++++++++++++++++++++++++
 
-By default variables are merged/flattened to the specific host before a play is run. This keeps Ansible focused on the Host and Task, so groups don't really survive outside of inventory and host matching. By default, Ansible overwrites variables including the ones defined for a group and/or host (see the `hash_merge` setting to change this) . The order/precedence is (from lowest to highest):
+By default variables are merged/flattened to the specific host before a play is run. This keeps Ansible focused on the Host and Task, so groups don't really survive outside of inventory and host matching. By default, Ansible overwrites variables including the ones defined for a group and/or host (see :ref:`DEFAULT_HASH_BEHAVIOUR<DEFAULT_HASH_BEHAVIOUR>`). The order/precedence is (from lowest to highest):
 
 - all group (because it is the 'parent' of all other groups)
 - parent group