DLTS → DTLS

Fix a typo that is confusing for newcomers.

CLA: trivial

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from #20909)

(cherry picked from commit 2913b5c)
(cherry picked from commit f8c2a15)

doc/man1/openssl.pod

@@ -573,7 +573,7 @@ B<s_client> and B<s_server> commands.
 
 =item B<-dtls>, B<-dtls1>, B<-dtls1_2>
 
-These options specify to use DTLS instead of DLTS.
+These options specify to use DTLS instead of TLS.
 With B<-dtls>, clients will negotiate any supported DTLS protocol version.
 Use the B<-dtls1> or B<-dtls1_2> options to support only DTLS1.0 or DTLS1.2,
 respectively.