public String render(CommandLine.Help help) {
			if (help.commandSpec().subcommands().isEmpty()) {
				return "";
			}

			StringBuilder result = new StringBuilder();

			sections.forEach((key, value) -> result.append(renderSection(key, value, help)));
			return result.toString();
		}
validate all commands in Help is covered by section and each section command
exist in help.

@param help
src/main/java/dev/jbang/cli/JBang.java