Update docs

docs/clients.md

@@ -9,3 +9,25 @@ To add a VPN connection, first securely transfer the generated `.ovpn` file to y
 To manage OpenVPN clients, run the install script again: `sudo bash openvpn.sh`.
 
 Read [:book: VPN book](https://ko-fi.com/post/Support-this-project-and-get-access-to-supporter-o-O5O7FVF8J) to learn step-by-step instructions to configure and manage OpenVPN clients.
+
+<details>
+<summary>
+View usage information for the OpenVPN script.
+</summary>
+
+```
+Usage: bash openvpn.sh [options]
+
+Options:
+  --auto                        auto install OpenVPN using default options
+  --addclient [client name]     add a new client
+  --exportclient [client name]  export configuration for an existing client
+  --listclients                 list the names of existing clients
+  --revokeclient [client name]  revoke an existing client
+  --uninstall                   remove OpenVPN and delete all configuration
+  -y, --yes                     assume "yes" as answer to prompts when revoking a client or removing OpenVPN
+  -h, --help                    show this help message and exit
+
+To customize install options, run this script without arguments.
+```
+</details>