The `transitional` property is not documented

**Describe the bug**

The `transitional` property is not documented

**To Reproduce**
Steps to reproduce the behavior:
1. Go to https://axios-http.com/docs/req_config
2. Search for "transitional"
3. No hits

**Expected behavior**

See https://github.com/axios/axios/blob/v1.x/README.md where `transitional` is documented.

I did not check, but I assume there is a risk of other discrepancies.