Added note to create NAT outbound rule for redirect-gateway to work (#554)

* Added note to create NAT outbound rule for redirect-gateway to work
https://github.com/opnsense/core/issues/7318

* Added a brief info abount redirect-gateway

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Co-authored-by: Thomas Cekal <admin@cekal.org>

source/manual/how-tos/sslvpn_instance_roadwarrior.rst

@@ -146,6 +146,7 @@ TLS static key          choose the prepared static key
 Authentication          Local Database  :sup:`2`
 Strict User/CN Matching [V]  :sup:`3`
 Local Network           192.168.8.0/24
+Redirect gateway        Leave empty :sup:`4`
 ======================= =======================================
 
 .. admonition:: Note  :sup:`1`
@@ -163,6 +164,10 @@ Local Network           192.168.8.0/24
    Selecting the "Strict User/CN Matching" option warrants only matching user/certificate can login, when sharing a single
    vertificate between clients this option needs to be deselected.
 
+.. admonition:: Note  :sup:`4`
+
+   If you want all outgoing IP traffic to be redirected over the VPN, you can set the option to :code:`default`.
+   For this to work, a manual NAT outbound rule must be created.
 
 Next go to :menuselection:`Firewall --> Rules --> WAN` and add a rule to allow traffic on port :code:`1194/UDP` from the other
 host. At minimum we should add a rule similar to this one: