Feature request short arguments in help text

[ConorSheehan1]

Saw short arguments were added in #141, which looks great!

I was wondering if it'd be possible to include the short args in help text too?

I was thinking something like, given:

# foo.py
import fire

def func(foo=False, bar='bar', baz='dupe'):
    pass

if __name__ == '__main__':
    fire.Fire(func)

The output could change like this:

# python foo.py --help
 FLAGS
-    --foo=FOO
+    -f, --foo=FOO
         Default: False
     --bar=BAR
         Default: 'bar'
     --baz=BAZ
         Default: 'dupe'

I'd be happy to try and pr this myself if you think it's worth adding?

[xiaoxstz]

If a parameter has no default value, it will be listed in POSITIONAL ARGUMENTS, and has no short argument; Otherwise, it will be listed in FLAGS.

If a parameter is listed in FLAGS, and its first character is exclusive, its first character will be set as its short name.

For example, save the script below to file test.py

import fire


def func(foo, bar='bar', baz='dupe',number=0):
    pass

if __name__ == '__main__':
    fire.Fire(func)

The help command python test.py -h outputs:

NAME
    test.py

SYNOPSIS
    test.py FOO <flags>

POSITIONAL ARGUMENTS
    FOO

FLAGS
    --bar=BAR
        Default: 'bar'
    --baz=BAZ
        Default: 'dupe'
    -n, --number=NUMBER
        Default: 0

NOTES
    You can also use flags syntax for POSITIONAL ARGUMENTS

PS：my test version: fire 0.6.0