Show a unified diff between two orb versions

## Usage

`circleci orb diff <namespace>/<orb> --from <v1> --to <v2> [flags]`

## Arguments

- `<namespace>/<orb>` is the orb to diff, for example, `namespace/orb-name`.

## Flags

| Flag            | Description                                                              |
| --------------- | ------------------------------------------------------------------------ |
| `--from string` | the first version (semver e.g. 1.0.0, or a dev label e.g. dev:my-branch) |
| `--to string`   | the second version, in the same form as --from                           |

Global flags: `-c, --config`, `--debug`, `--no-color`, `-q, --quiet` — see `circleci --help`.

## Examples

- Diff two semver versions: 
  `circleci orb diff myorg/my-orb --from 1.0.0 --to 1.1.0`
- Diff a semver and a dev version: 
  `circleci orb diff myorg/my-orb --from 1.0.0 --to dev:my-branch`
- Diff two dev versions: 
  `circleci orb diff myorg/my-orb --from dev:branch-a --to dev:branch-b`

## Details

Show a unified diff between two versions of an orb.

The --from and --to versions can be semver (e.g. 1.0.0) or dev labels
(e.g. dev:my-branch).

Exit code is 0 regardless of whether the versions differ.

