Render the help text for a topic. This is the single entry point the CLI
calls when it has decided to print help: it dispatches to the general block
or one of the subcommand blocks. The result is exactly the string to
write to stdout — it ends with a trailing newline.
Render the help text for a topic. This is the single entry point the CLI calls when it has decided to print help: it dispatches to the general block or one of the subcommand blocks. The result is exactly the string to write to stdout — it ends with a trailing newline.