Update README.md to include API specification

README.md

@@ -10,3 +10,54 @@ Then start the Express framework using:
 ```
 node index.js
 ```
+
+# API
+
+### /hello/:name/
+Returns "Hello :name!" or simply "Hello World!" if no name is present. :)
+
+### /register/
+In order to register a new user account, a `POST` request should be sent, with
+the following data:
+```
+{
+    "user": desired_username_here,
+    "password": desired_password_here
+}
+```
+The server will then respond with a JSON object that looks something like this:
+```
+{
+    "registered": 1, // Value is 1 or 0 based on whether registration was
+    successful
+    "auth-key": $2a$10$.X9YrNyd2R7b2ycAumHn.ONiINs2bCkRDupugu6sjZkUkPmXSaSra, //
+    Value is an authentication key to be used in API requests
+    "error": 0 // Error code, if an error occured. 0 indicates no error.
+}
+```
+The value of the error code will be `1` if the username already exists.
+
+### /login/
+In order to log into an account, or essentially request a new authentication
+token, a `POST` request should be sent with the following data:
+```
+{
+    "user": username_here,
+    "password": password_here, // Optional field if auth-key is present
+    "auth-key": auth_key_here // Optional field if password is present
+}
+```
+Using the auth-key will reset and generate a new authentication key, whereas
+password will simply get the current auth-key. In either case the following data
+will be returned:
+```
+{
+    "logged_in": 1, // Value is 1 or 0 whether or not the login was successful
+    "auth-key": $2a$10$.X9YrNyd2R7b2ycAumHn.ONiINs2bCkRDupugu6sjZkUkPmXSaSra, //
+    Only present if logged_in == 1, to be used in API requests
+    "error": 0 // Error code, if an error occured. 0 indicates no error.
+}
+```
+The error codes are as follows, 1 indicates the username could not be found, 2
+indicates that the password is invalid and 3 indicates the provided
+authentication key was invalid.