src: include warning in the secret file

src/keypair.rs

@@ -59,7 +59,16 @@ impl SSBKeypair for Keypair {
         } else {
             let mut csprng = OsRng {};
             let keypair = Keypair::generate(&mut csprng);
-            std::fs::write(path, keypair.to_json().pretty(2)).unwrap();
+            let keypair_json = keypair.to_json();
+            std::fs::write(
+                path,
+                format!(
+                    include_str!("warning.txt"),
+                    keys = keypair_json.pretty(2),
+                    id = keypair_json["id"]
+                ),
+            )
+            .unwrap();
             keypair
         }
     }

src/warning.txt

@@ -0,0 +1,15 @@
+# WARNING: Never show this to anyone.
+# WARNING: Never edit it or use it on multiple devices at once.
+#
+# This is your SECRET, it gives you magical powers. With your secret you can
+# sign your messages so that your friends can verify that the messages came
+# from you. If anyone learns your secret, they can use it to impersonate you.
+#
+# If you use this secret on more than one device you will create a fork and
+# your friends will stop replicating your content.
+#
+{keys}
+#
+# The only part of this file that's safe to share is your public name:
+#
+#   {id}