Fixed several readability issues in DH_generate_parameters.pod

Reviewed-by: NTim Hudson <tjh@openssl.org>
Reviewed-by: NMatthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/5553)

doc/man3/DH_generate_parameters.pod

@@ -111,10 +111,10 @@ The parameter B<j> is invalid.
 
 =back
 
-DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() are similiar with
-DH_check() and DH_check_params() respectively, but the error reasons are set
-to the OpenSSL error handling framework instead of returning by the function
-parameters.
+DH_check_ex(), DH_check_params() and DH_check_pub_key_ex() are similar to
+DH_check() and DH_check_params() respectively, but the error reasons are added
+to the thread's error queue instead of provided as return values from the
+function.
 
 =head1 RETURN VALUES