Add documentation for fetch -n option

Author: eritbh

README.md

@@ -14,6 +14,12 @@ Ensure that you also have the [1Password CLI](1password-cli) available as `op` v
 
 [1password-cli]: https://support.1password.com/command-line-getting-started/
 
+### Automatically fetch keys before using SSH
+
+In bash/zsh, you can define an alias for the `ssh` command which ensures your keys are fetched before connecting to a server, like so:
+
+    alias ssh="op-ssh-fetch -n [arguments to 'op signin']; ssh"
+
 ## Usage
 
 Note that interactive execution is not supported for any of these scripts, since `op signin` is required for all scripts and itself requires interactive password input.
@@ -35,6 +41,8 @@ Create a new vault item associated with the given host and the current username,
 
 Search for SSH key items in your vault and read them all into temporary storage. Public and private keys will be saved to `/tmp/op-ssh-utils/keys` with appropriate permissions, and an SSH config file will be saved to `/tmp/op-ssh-utils/ssh_config` which can be included from your personal SSH config (usually `~/.ssh/config`) via `Include /tmp/op-ssh-utils`.
 
+- Use `-n` to do nothing if keys already exist. This is useful for shell aliases.
+
 ### Remove all local SSH credentials
 
     $ op-ssh-remove