doc: Advise the user to generate PEM keys.

With openssh-7.8 the default has been changed to write OpenSSH format
private keys instead of OpenSSL's PEM format. paraslash can only read
the latter, so make sure everyone stays at PEM for now.

diff --git a/web/manual.md b/web/manual.md
index 04c716a87da88b81ab43ef01f15c8067bef46ea3..e0f5ccf1866d06378d249b3177a923fb6d8aa502 100644 (file)
--- a/web/manual.md
+++ b/web/manual.md
@@ -446,7 +446,7 @@ following commands:
 Next, change to the "bar" account on client_host and generate the
 key pair with the commands
 
-       ssh-keygen -q -t rsa -b 2048 -N '' -f $key
+       ssh-keygen -q -t rsa -b 2048 -N '' -m PEM -f $key
 
 This generates the two files id_rsa and id_rsa.pub in ~/.ssh.  Note
 that para_server won't accept keys shorter than 2048 bits. Moreover,