Improve CLI Text by Adding Verbose Text for Commands

[rtadepalli]

Add some verbose descriptions (similar to PyIceberg) for the CLI options when iceberg --help is used.

Closes #61

[rtadepalli]

Kept the existing set of usages because this line for example has iceberg command [options] namespace and then an argument -- the namespace part isn't fully captured in the iceberg command [options] [arguments] format. Thought it'd be better to just leave these as examples.

[rtadepalli]

@zeroshade can you please take a look at this?

[zeroshade]

does this actually work? The library being used docopt actually uses the usage string to perform the parsing and processing. [options] is a special handle thing for docopt, but i don't think that [command] and [arguments] is. So i think this might break the CLI here

[rtadepalli]

@zeroshade Apologies, this slipped through my radar. I don't think that this is breaking the CLI:

~/Software/iceberg-go/cmd/iceberg (improve-cli-help-text*) » ./iceberg --help                                                                                                                             ramasai@Ramasais-MacBook-Air
iceberg.

Usage:
  iceberg [command] [options] [arguments]
  iceberg -h | --help
  iceberg --version

Commands:
  describe    Describe a namespace or a table.
  list        List tables or namespaces.
  schema      Get the schema of the table.
  spec        Return the partition spec of the table.
  uuid        Return the UUID of the table.
  location    Return the location of the table.
  drop        Operations to drop a namespace or table.
  files       List all the files of the table.
  rename      Rename a table.
  properties  Properties on tables/namespaces.

Arguments:
  PARENT         Catalog parent namespace
  IDENTIFIER     fully qualified namespace or table
  TABLE_ID       full path to a table
  PROPNAME       name of a property
  VALUE          value to set

Options:
  --catalog TEXT     specify the catalog type [default: rest]
  --uri TEXT         specify the catalog URI
  --output TYPE      output type (json/text) [default: text]
  --credential TEXT  specify credentials for the catalog
  --warehouse TEXT   specify the warehouse to use

Example Usages
  iceberg list [options] [PARENT]
  iceberg describe [options] [namespace | table] IDENTIFIER
  iceberg (schema | spec | uuid | location) [options] TABLE_ID
  iceberg drop [options] (namespace | table) IDENTIFIER
  iceberg files [options] TABLE_ID [--history]
  iceberg rename [options] <from> <to>
  iceberg properties [options] get (namespace | table) IDENTIFIER [PROPNAME]
  iceberg properties [options] set (namespace | table) IDENTIFIER PROPNAME VALUE
  iceberg properties [options] remove (namespace | table) IDENTIFIER PROPNAME

I tested this before putting up the PR -- unless I am misunderstanding what you mean?

[zeroshade]

That's for the help, did you confirm that it works just fine for the regular usages of calling list/describe/files/etc.? it's just a usage for docopt i hadnt seen before

[zeroshade]

@rtadepalli I like the idea in general, but could you address my question when you have a chance?