init: better borg key export instructions

src/borg/archiver.py

@@ -323,9 +323,18 @@ class Archiver:
             logger.warning(
                 '\n'
                 'IMPORTANT: you will need both KEY AND PASSPHRASE to access this repo!\n'
-                'If you used a repokey mode, the key is stored in the repo, but you should back it up separately.\n'
-                'Use "borg key export" to export the key, optionally in printable format.\n'
-                'Write down the passphrase. Store both at safe place(s).\n')
+                '\n'
+                'Key storage location depends on the mode:\n'
+                '- repokey modes: key is stored in the repository directory.\n'
+                '- keyfile modes: key is stored in the home directory of this user.\n'
+                '\n'
+                'For any mode, you should:\n'
+                '1. Export the borg key and store the result at a safe place:\n'
+                '   borg key export           REPOSITORY encrypted-key-backup\n'
+                '   borg key export --paper   REPOSITORY encrypted-key-backup.txt\n'
+                '   borg key export --qr-html REPOSITORY encrypted-key-backup.html\n'
+                '2. Write down the borg key passphrase and store it at safe place.\n'
+            )
 
     @with_repository(exclusive=True, manifest=False)
     def do_check(self, args, repository):