cryptenroll,homectl,journalctl: adjust messages before qrcodes

Users will generally know what a qrcode is, so let's not treat them as dumb and
explain that it can be scanned. OTOH, we should say what the qrcode contains
and it is useful to give a hint why the users would want to scan it. Reword
messages accordingly.

(Also, don't say "to your phone", when somebody might be using a stolen phone,
or something else then a phone.)

src/cryptenroll/cryptenroll-recovery.c

@@ -67,7 +67,7 @@ int enroll_recovery(
               "whenever authentication is requested.\n", stderr);
         fflush(stderr);
 
-        (void) print_qrcode(stderr, "You may optionally scan the recovery key off screen", password);
+        (void) print_qrcode(stderr, "Optionally scan the recovery key for safekeeping", password);
 
         if (asprintf(&keyslot_as_string, "%i", keyslot) < 0) {
                 r = log_oom();

src/home/homectl-recovery-key.c

@@ -160,7 +160,7 @@ int identity_add_recovery_key(sd_json_variant **v) {
               "whenever authentication is requested.\n", stderr);
         fflush(stderr);
 
-        (void) print_qrcode(stderr, "You may optionally scan the recovery key off screen", password);
+        (void) print_qrcode(stderr, "Optionally scan the recovery key for safekeeping", password);
 
         return 0;
 }

src/journal/journalctl-authenticate.c

@@ -199,9 +199,7 @@ int action_setup_keys(void) {
         if (!url)
                 return log_oom();
 
-        (void) print_qrcode(stderr,
-                            "To transfer the verification key to your phone scan the QR code below",
-                            url);
+        (void) print_qrcode(stderr, "Scan the verification key to transfer it to another device", url);
 #endif
 
         return 0;