Fix description on module page

@darkdim can you provide the updated steps?

Here are the updated steps for the Google Console side of things (will create this as an MR to the readme as well):

1. Log in to a Google account.
2. In the project picker it will default to 'My First Project'. Click that to optionally create a new project with a more appropriate name.
3. If you created a new project, select the project you created from the welcome page https://console.cloud.google.com/welcome once it is available.
4. Under 'Quick access' click 'APIs and services'
5. Navigate to 'OAuth consent screen' and click 'Get started'.
6. Under App Information, set the App name and User support email then click 'Next'.
7. Set the Audience to 'External' then click 'Next'.
8. Set your contact information then click 'Next'
9. Read and - if you agree to the Google API services data policy terms and conditions - check the box and click 'Continue'.
10. Finalise by clicking 'Create'.
11. You are taken to the 'OAuth overview'. Click 'Create OAuth client'.
12. Select "Web application" in the Application type field.
13. Set the Name field as desired.
14. In the Authorized redirect URIs section click Add URI.
15. Paste the URL copied from Step 2 in the URI field (the URI found in the 'Authorized redirect URL' within your Admin > Configuration > Social API > (Provider) settings page). Multiple URIs can be entered if you wish to allow multiple environments to use this Social Authentication.
16. Click Create.
17. Copy the new 'Client ID' save it somewhere safe.
18. Click on the newly created Client from the Clients list to find the 'Client secret' and optionally manage secrets. From here you can also add additional 'Authorised redirect URIs' for additional environments.
19. Note that it may take up to 5 minutes for changes to take effect.

Note that the UI is completely revamped and more than what is highlighted in the issue summary has changed; namely:

1. The creation of a project process is different
2. The setup of a Client is different
3. Obtaining the Secret is no longer a one-time thing and happens at a different step

I added details for adding multiple Redirect URIs as well