Point out that paperkey backups are password-protected

Fixes drduh#263. Really though decision to make whether a paper printout with the password is a good way to go (recoverable but needs a really good place to keep) or not (more protection, but possibly worthless).

README.md

@@ -951,10 +951,12 @@ The `revoke.asc` certificate file should be stored (or printed) in a (secondary)
 
 # Backup
 
-Once keys are moved to YubiKey, they cannot be moved again! Create an **encrypted** backup of the keyring and consider using a [paper copy](https://www.jabberwocky.com/software/paperkey/) of the keys as an additional backup measure.
-
+Once keys are moved to YubiKey, they cannot be moved again! Create an **encrypted** backup of the keyring on removable media so you can keep it offline in a safe place.
+	
 **Tip** The ext2 filesystem (without encryption) can be mounted on both Linux and OpenBSD. Consider using a FAT32/NTFS filesystem for MacOS/Windows compatibility instead.
 
+As an additional backup measure, consider using a [paper copy](https://www.jabberwocky.com/software/paperkey/) of the keys. The [Linux Kernel Maintainer PGP Guide](https://www.kernel.org/doc/html/latest/process/maintainer-pgp-guide.html#back-up-your-master-key-for-disaster-recovery) points out that such printouts *are still password-protected*. It recommends to *write the password on the paper*, since it will be unlikely that you remember the original key password that was used when the paper backup was created. Obviously, you need a really good place to keep such a printout.
+
 **Linux**
 
 Attach another external storage device and check its label: