Improve messaging so that users know how to set their initial admin p…

…assword

Signed-off-by: Derek Ho <[email protected]>

src/main/java/org/opensearch/security/tools/democonfig/SecuritySettingsConfigurer.java

@@ -149,7 +149,7 @@ void updateAdminPassword() {
 
             // if ADMIN_PASSWORD is still an empty string, it implies no custom password was provided. We exit the setup.
             if (Strings.isNullOrEmpty(ADMIN_PASSWORD)) {
-                System.out.println("No custom admin password found. Please provide a password.");
+                System.out.println("No custom admin password found. Please provide a password via the environment variable OPENSEARCH_INITIAL_ADMIN_PASSWORD.");
                 System.exit(-1);
             }