docs: add ssh key for vmware doc

os/ssh-vmware.md

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+# Adding SSH keys for VMWare
+
+Most installations of Container Linux on VMWare require an SSH key to access the machine. Use a [Container Linux Config][cl-config] with a valid SSH key and the [Config Transpiler][config-transpiler] to create the ignition config. Then pass that ignition config to the VMWare image’s VMX file to enable SSH access to the machine.
+
+Modify the VMX file to pass an [Ignition Config][ignition-config] containing at least one valid SSH key.
+
+First, follow the instructions to Boot with VMware Workstation 12 or VMware Fusion to create a VM. (Do not start / power on the the VM. These instructions will work only on the first boot.)
+
+Next, create and apply the SSH key:
+
+1. [Download Config Transpiler][download-ct].
+
+2. Follow the instructions to [add an SSH public key][add-ssh] to the Container Linux Config (for example `id_rsa.pub`).
+
+```
+passwd:
+  users:
+    - name: core
+      ssh_authorized_keys:
+        - "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC0g+ZTxC7weoIJLUafOgrm+h..."
+```
+
+3. Use Config Transpiler to convert the Container Linux Config YAML to Ignition Config, then base64 encode the Ignition config.
+
+```
+$ ./ct --in-file config.yaml | base64
+```
+
+Remove any newline characters from the encoded output.
+
+4. Open the VM’s VMX file in your favorite text editor, and add the base64 encoded Ignition Config to the VMWare image’s VMX file under Guestinfo as outlined in [Defining the Ignition config in Guestinfo][define-guestinfo].
+
+```
+guestinfo.coreos.config.data = "<<Output of the base64 encoded ignition file>>>"
+guestinfo.coreos.config.data.encoding = "base64"
+```
+
+5. Save the VMX file and boot the VM for the first time.
+
+Once booted, use `$ ssh core@<<ip address>>` to SSH into the machine. If you haven’t added the SSH key to the SSH agent, specify the key using the `-i` flag:
+
+`$ ssh -i <<path to ssh public key>> core@<<ip address>>`
+
+
+[add-ssh]: https://coreos.com/os/docs/latest/migrating-to-clcs.html#ssh_authorized_keys
+[config-transpiler]: https://coreos.com/os/docs/latest/overview-of-ct.html
+[define-guestinfo]: https://coreos.com/os/docs/latest/booting-on-vmware.html#defining-the-ignition-config-in-guestinfo
+[download-ct]: https://github.com/coreos/container-linux-config-transpiler/releases/
+[ignition-config]: https://coreos.com/os/docs/latest/provisioning.html#ignition-config
+[cl-config]: https://coreos.com/os/docs/latest/provisioning.html