Subcommand not recognized if followed by a # HEADER line

[eaubin]

For example, mask foo --help on

# Header 1

## foo

### foo A

```sh
echo A
```

### foo B

```sh
echo B
```

# foo B is not found as a subcommand if this line is present

prints

mask-foo 


USAGE:
    mask foo <SUBCOMMAND>

FLAGS:
    -h, --help    Prints help information

SUBCOMMANDS:
    A       
    help    Prints this message or the help of the given subcommand(s)