README.md does not properly describe subcommands

[gizmomogwai]

e.g. for me --help does not print the subcommands if I do not Annotate their SumType with @SubCommands. Also the first subsection reads Subcommands without UDA which indices for me, that there is a way to do subcommands without and with uda ... but its kind of the same, just the subcommands are configured with udas ...

[andrey-zherikov]

argparse supports two use cases:

• without UDAs meaning no PositionalArgument, NamedArgument, SubCommands
• with UDAs meaning that only annotated members are considered

The switch is: if there is at least one member with PositionalArgument, NamedArgument or SubCommands then the second approach is used.

[andrey-zherikov]

@gizmomogwai any objections if I close this in favor of #78? Both are about mixing *Argument and Sub Commands UDAs

[gizmomogwai]

No problem ... please close... I was not sure if this is one or two issues :)