Documentation Typo

PR incoming.

## Environment data

- debugpy version: '1.8.14+1.g4bc7343c.dirty'
- OS and version: Ubuntu 22
- Python version (& distribution if applicable, e.g. Anaconda): 12
- Using VS Code or Visual Studio: Yes--VS Code.

## Actual behavior

`tox --developer` raises error.

## Expected  behavior

`tox --develop` works.

## Steps to reproduce:
1. `cd` to root of project
2. Run `tox --developer`
