There are no code changes required to make this work. I added a test
specifying `<owner>/<number>` and nothing failed. Any syntax issues are
returned by the api with a generic message:
```
Invalid search query "project:\"<string>\" type:issue".
An invalid project was specified.
```
This, combined with the updated docstring, should be sufficient for users
to troubleshoot any issues with the `--project` flag syntax
Found with
rg '(^ | \t|\t )' -g '*.go' -g '!*_test.go'
Mixed indent exceptions:
- wrapped long list items with extra 2-space indent
- code snippets using space indent
- commented code lines having "\t*// \t+" prefix
