doc(scw): add SCW_PROFILE env var (#257)

Author: Quentin Brosse

scw/README.md

@@ -52,3 +52,4 @@ scw.NewClient(
 | `$SCW_DEFAULT_ZONE`       | Your default [availability zone](https://developers.scaleway.com/en/quickstart/#region-and-zone)                                        | `$SCW_ZONE` (used by cli),`$SCALEWAY_ZONE` (used by terraform)                                                |
 | `$SCW_API_URL`            | Url of the API                                                                                                                          | -                                                                                                             |
 | `$SCW_INSECURE`           | Set this to `true` to enable the insecure mode                                                                                          | `$SCW_TLSVERIFY` (inverse flag used by the cli)                                                               |
+| `$SCW_PROFILE`            | Set the config profile to use                                                                                                           | -                                                                                                             |