Put the full help before the options

Summary: This is more in line with "traditional" output from cli tools on *nix.

Reviewed By: yfeldblum

Differential Revision: D4719055

fbshipit-source-id: 2389a4a2a49f18d4b3d0257f68036f73f8fbc49e

folly/experimental/NestedCommandLineApp.cpp

@@ -143,14 +143,14 @@ void NestedCommandLineApp::displayHelp(
         info.argStr.empty() ? "" : " ",
         info.argStr.c_str());
 
+    printf("%s\n", info.fullHelp.c_str());
+
     std::cout << globalOptions_;
 
     if (!info.options.options().empty()) {
       printf("\n");
       std::cout << info.options;
     }
-
-    printf("\n%s\n", info.fullHelp.c_str());
   }
 }