nixos/manual: fix sshfs keygen output

Changed files
+2 -2
nixos
doc
manual
+2 -2
nixos/doc/manual/configuration/sshfs-file-systems.section.md
···
```ShellSession
$ ssh-keygen -t ed25519 -P '' -f example-key
Generating public/private ed25519 key pair.
-
Your identification has been saved in test-key
-
Your public key has been saved in test-key.pub
The key fingerprint is:
SHA256:yjxl3UbTn31fLWeyLYTAKYJPRmzknjQZoyG8gSNEoIE my-user@workstation
```
···
```ShellSession
$ ssh-keygen -t ed25519 -P '' -f example-key
Generating public/private ed25519 key pair.
+
Your identification has been saved in example-key
+
Your public key has been saved in example-key.pub
The key fingerprint is:
SHA256:yjxl3UbTn31fLWeyLYTAKYJPRmzknjQZoyG8gSNEoIE my-user@workstation
```