Remove --key-name from OpenStack examples, clarify SSH key is in cloud-init

deploy/README.md

@@ -27,7 +27,9 @@ Customize `cloud-init.yml` — replace the SSH public key and optionally the hos
 
 #### Full OpenStack example
 
-Cloud-init only handles guest configuration — flavor, image, network, and security group must be specified explicitly at creation time:
+Cloud-init only handles guest configuration — flavor, image, network, and security group must be specified explicitly at creation time.
+
+> **Note:** Do not use `--key-name` — the SSH key is configured in `cloud-init.yml` under `ssh_authorized_keys` for the `devbox` user. The `--key-name` flag injects into the image's default user (e.g. `debian`), not the `devbox` user created by cloud-init.
 
 ```bash
 # List available flavors to choose appropriate sizing
@@ -42,7 +44,6 @@ openstack server create \
   --image debian-13-trixie \
   --network my-network \
   --security-group opencode-devbox \
-  --key-name my-ssh-key \
   --user-data cloud-init.yml \
   devbox-vm
 ```
@@ -55,7 +56,6 @@ openstack server create \
   --flavor c4m8 \
   --network my-network \
   --security-group opencode-devbox \
-  --key-name my-ssh-key \
   --user-data cloud-init.yml \
   --block-device source=image,id=$(openstack image show debian-13-trixie -f value -c id),dest=volume,size=40,shutdown=preserve,bootindex=0,volume_type=performance \
   devbox-vm