pkey: update command line tool examples in light of deprecations.

Specifically, refer from the deprecated tools to the pkey equivalents.
Reviewed-by: NDmitry Belyavskiy <beldmit@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/11113)

doc/man1/openssl-dsa.pod.in

@@ -127,6 +127,9 @@ a public key.
 
 =head1 EXAMPLES
 
+Examples equivalent to these can be found in the documentation for the
+non-deprecated L<openssl-pkey(1)> command.
+
 To remove the pass phrase on a DSA private key:
 
  openssl dsa -in key.pem -out keyout.pem

doc/man1/openssl-ec.pod.in

@@ -145,6 +145,9 @@ This option checks the consistency of an EC private or public key.
 
 =head1 EXAMPLES
 
+Examples equivalent to these can be found in the documentation for the
+non-deprecated L<openssl-pkey(1)> command.
+
 To encrypt a private key using triple DES:
 
  openssl ec -in key.pem -des3 -out keyout.pem

doc/man1/openssl-ecparam.pod.in

@@ -134,6 +134,9 @@ This option will generate an EC private key using the specified parameters.
 
 =head1 EXAMPLES
 
+Examples equivalent to these can be found in the documentation for the
+non-deprecated L<openssl-genpkey(1)> and L<openssl-pkeyparam(1)> commands.
+
 To create EC parameters with the group 'prime192v1':
 
   openssl ecparam -out ec_param.pem -name prime192v1

doc/man1/openssl-pkey.pod.in

@@ -120,7 +120,7 @@ of a key pair.
 
 =head1 EXAMPLES
 
-To remove the pass phrase on an RSA private key:
+To remove the pass phrase on a private key:
 
  openssl pkey -in key.pem -out keyout.pem
 

doc/man1/openssl-rsa.pod.in

@@ -140,6 +140,9 @@ Like B<-pubin> and B<-pubout> except B<RSAPublicKey> format is used instead.
 
 =head1 EXAMPLES
 
+Examples equivalent to these can be found in the documentation for the
+non-deprecated L<openssl-pkey(1)> command.
+
 To remove the pass phrase on an RSA private key:
 
  openssl rsa -in key.pem -out keyout.pem

doc/man1/openssl-rsautl.pod.in

@@ -135,6 +135,9 @@ used to sign or verify small pieces of data.
 
 =head1 EXAMPLES
 
+Examples equivalent to these can be found in the documentation for the
+non-deprecated L<openssl-pkeyutl(1)> command.
+
 Sign some data using a private key:
 
  openssl rsautl -sign -in file -inkey key.pem -out sig