LibCore: Offer to display a general description

Author: https://github.com/BenWiederhake
Commit: 52a8062084
Pull-request: https://github.com/SerenityOS/serenity/pull/4332

Libraries/LibCore/ArgsParser.cpp

@@ -206,6 +206,11 @@ void ArgsParser::print_usage(FILE* file, const char* argv0)
     }
     outln(file);
 
+    if (m_general_help != nullptr && m_general_help[0] != '\0') {
+        outln(file, "\nDescription:");
+        outln(file, m_general_help);
+    }
+
     if (!m_options.is_empty())
         outln(file, "\nOptions:");
     for (auto& opt : m_options) {