Add authentication info to README

authserver/README.md

@@ -15,7 +15,29 @@ $ . env/bin/activate
 
 ## API
 
-The API is RESTful and returns hyperlinked json data. URLs require a trailing slash.
+The API is RESTful and returns hyperlinked json data. **URLs require a trailing slash.**
+
+### Authentication
+
+Authentication is token-based and done against the Protospace member portal. Upon successful login, the auth server will automatically register the user and create them a profile.
+
+#### POST `/login/`
+
+POST data `username` and `password`. Upon successful login, a 200 status and a token will be returned.
+
+Example response:
+
+```
+{
+    "token": "9944b09199c62bcf9418ad846dd0e4bbdfc6ee4b"
+}
+```
+
+In subsequent requests, the token key should be included in the `Authorization` HTTP header. The key should be prefixed by the string literal "Token", with whitespace separating the two strings. For example:
+
+```
+Authorization: Token 9944b09199c62bcf9418ad846dd0e4bbdfc6ee4b
+```
 
 ### For anonymous users