add some google oauth2 docs

README.md

@@ -1,3 +1,37 @@
 # go-mockid
 
-OAuth2 / JWT / OpenID Connect for mocking auth... which isn't that different from doing it for real, actually.
+OAuth2 / JWT / OpenID Connect for mocking auth... which isn't that different from doing it for real, actually.
+
+## Enabling Google OAuth2 (Mid-2020)
+
+1. Create an account at https://console.developers.google.com/apis/dashboard
+2. Go back to https://console.developers.google.com/apis/dashboard
+3. Create a New Project from the dropdown in the upper left that lists the current project name
+  4. Give the project a name such as `Example Web App` and accept its generated ID
+  5. Click "Create"
+
+Add your test domain
+
+0. Go back to https://console.developers.google.com/apis/dashboard
+1. Select your new project from the upper-left drop-down
+2. Select `Domain Verification` from the left hand side of the screen
+3. Add your test domain (i.e. `beta.example.com`), but a domain that you actually own
+4. Select `Verify Ownership`
+5. Follow the specific instructions for adding a txt record to the subdomain you chose
+6. Add a collaborator / co-owner if you wish
+
+Enable OAuth2
+
+0. Go back to https://console.developers.google.com/apis/dashboard
+1. Select `OAuth consent screen`
+2. Select `External`
+3. Complete the consent screen form
+
+Create Google Credentials
+
+0. Go back to https://console.developers.google.com/apis/dashboard
+1. Select `Credentials` from the left sidebar
+2. Select `OAuth ID`
+3. Select `Web Application`
+4. Fill out the same test domain and test app name as before
+5. Save the ID and Secret to a place you won't forget (perhaps a .gitignored .env)