add oidc-related help to pscp

pscp.c

@@ -2202,6 +2202,12 @@ static void usage(void)
     printf("  -C        enable compression\n");
     printf("  -i key    private key file for user authentication\n");
     printf("  -noagent  disable use of Pageant\n");
+    printf("  -oidc-agent configuration\n");
+    printf("            enable use of oidc-agent with given (loaded) configuration\n");
+    printf("  -mc-host  host\n");
+    printf("            use custom motley_cue endpoint to deploy the remote user (OIDC)\n");
+    printf("  -mc-port  port\n");
+    printf("            use custom motley_cue port to deploy the remote user (OIDC)\n");
     printf("  -agent    enable use of Pageant\n");
     printf("  -no-trivial-auth\n");
     printf("            disconnect if SSH authentication succeeds trivially\n");