Fix doctool misleading error message

main/main.cpp

@@ -1509,7 +1509,7 @@ bool Main::start() {
 
 		{
 			DirAccessRef da = DirAccess::open(doc_tool);
-			ERR_FAIL_COND_V_MSG(!da, false, "Argument supplied to --doctool must be a base Godot build directory.");
+			ERR_FAIL_COND_V_MSG(!da, false, "Argument supplied to --doctool must be a valid directory path.");
 		}
 		DocData doc;
 		doc.generate(doc_base);