Azure CLI dont have option to deploy a particular stage of a release.

- If the issue is to do with Azure CLI 2.0 in-particular, create an issue here at [Azure/azure-cli](https://github.com/Azure/azure-cli/issues)

### Extension name (the extension in question)

### Description of issue (in as much detail as possible)

-----
we issue below to get the list of releases:
`az pipelines release list --org https://dev.azure.com// --project `

Then we want to deploy a particular stage of a release from above list.
I dont see any way to do that.
Is it not supported by Azure CLI at this point?
Below are the version I am using:
```
azure-cli 2.3.1
command-modules-nspkg 2.0.3
core 2.3.1
nspkg 3.0.4
telemetry 1.0.4
Extensions:
azure-devops 0.18.0
```

Start by reviewing the azure-devops extension behavior and help for `az pipelines release list`, then check how release deployment commands expose stage selection. Done means a user can deploy a specified stage of a release returned by the listing command, with the supported syntax and behavior documented.

Written by the indexing model from the issue text.