Added
- `poll` section to *Bot* documentation
Changed
- `send` is now a group type of command which has `message`, `file` and `poll`
subcommands.
- Moved file sending functionality from `send` to `send file`
- Moved message sending functionality from `send` to `send message`
- `send` now only takes receiver chat id, other subcommands take related
options and parameters
- Updated *Bot* section of documentation