Update README.md (#3062)

README.md

@@ -656,7 +656,7 @@ openssl req -new -sha256 -key server.key \
     -config <(cat my-openssl.cnf <(printf "\n[SAN]\nsubjectAltName=DNS:localhost,IP:127.0.0.1,DNS:example.server.com")) \
     -out server.csr
 
-openssl x509 -req -days 365 \
+openssl x509 -req -days 365 -sha256 \
 	-in server.csr -CA ca.crt -CAkey ca.key -CAcreateserial \
 	-extfile <(printf "subjectAltName=DNS:localhost,IP:127.0.0.1,DNS:example.server.com") \
 	-out server.crt
@@ -671,7 +671,7 @@ openssl req -new -sha256 -key client.key \
     -config <(cat my-openssl.cnf <(printf "\n[SAN]\nsubjectAltName=DNS:client.com,DNS:example.client.com")) \
     -out client.csr
 
-openssl x509 -req -days 365 \
+openssl x509 -req -days 365 -sha256 \
     -in client.csr -CA ca.crt -CAkey ca.key -CAcreateserial \
 	-extfile <(printf "subjectAltName=DNS:client.com,DNS:example.client.com") \
 	-out client.crt