Added Key Authentication Option to SSH Tunneling Docs (#42206)

* Update ssh-tunnel.md

Add SSH key authentication option to SSH tunneling docs

* Update docs/databases/ssh-tunnel.md

Co-authored-by: Jeff Bruemmer <jeff.bruemmer@gmail.com>

* Update docs/databases/ssh-tunnel.md

Co-authored-by: Jeff Bruemmer <jeff.bruemmer@gmail.com>

* Update docs/databases/ssh-tunnel.md

Co-authored-by: Jeff Bruemmer <jeff.bruemmer@gmail.com>

---------

Co-authored-by: Jeff Bruemmer <jeff.bruemmer@gmail.com>

docs/databases/ssh-tunnel.md

@@ -28,7 +28,18 @@ When connecting though a bastion host:
 - Enter the data warehouse port as seen from inside the network into the `Port` parameter.
 - Enter the external name of the bastion host as seen from the outside of the network (or wherever you are) into the `SSH tunnel host` parameter.
 - Enter the SSH port as seen from outside the network into the `SSH tunnel port` parameter. This is usually 22, regardless of which data warehouse you are connecting to.
-- Enter the username and password you use to login to the bastion host into the `SSH tunnel username` and `SSH tunnel password` parameters.
+
+For authentication, you have two options:
+
+- **Using a username and password:**
+
+  - In the `SSH tunnel username` and `SSH tunnel password` fields, enter the username and password you use to log in to the bastion host.
+
+- **Using SSH key (PKI authentication):**
+
+  - Select SSH Key for the `SSH authentication` option.
+  - Paste the contents of your SSH private key into the `SSH private key` field.
+  - If your key has a passphrase, enter it into the `Passphrase for the SSH private key` field.
 
 If you're unable to connect test your SSH credentials by connecting to the SSH server/Bastion Host using ssh directly:
 
@@ -43,7 +54,7 @@ Another common case where direct connections are impossible is when connecting t
 - Enter the same value in the `Port` parameter that you would use if you where sitting directly at the data warehouse host system.
 - Enter the extenal name of the data warehouse, as seen from the outside of the network (or wherever you are) into the `SSH tunnel host` parameter.
 - Enter the SSH port as seen from outside the network into the `SSH tunnel port` parameter. This is usually 22, regardless of which data warehouse you are connecting to.
-- Enter the username and password you use to login to the bastion host into the `SSH tunnel username` and `SSH tunnel password` parameters.
+- Choose your authentication method as described above (username and password or SSH key).
 
 If you have problems connecting, verify the SSH host port and password by connecting manually using ssh or PuTTY on older windows systems.