document signature verification via macOS OpenSSH

static/install/cli.html

@@ -431,9 +431,7 @@ <h2><a href="#obtaining-factory-images">Obtaining factory images</a></h2>
                 <pre>curl -O https://releases.grapheneos.org/<var>DEVICE_NAME</var>-factory-2021110122.zip
 curl -O https://releases.grapheneos.org/<var>DEVICE_NAME</var>-factory-2021110122.zip.sig</pre>
 
-                <p>Verify the factory images using the signature if you were able to obtain OpenSSH
-                from trusted package repositories (see above), otherwise continue on to the next
-                section without this:</p>
+                <p>On Linux and macOS, verify the factory images using the signature:</p>
 
                 <pre>ssh-keygen -Y verify -f allowed_signers -I [email protected] -n "factory images" -s <var>DEVICE_NAME</var>-factory-2021110122.zip.sig &lt; <var>DEVICE_NAME</var>-factory-2021110122.zip</pre>