docs(reference): email is a mandatory parameter

Author: Matthew Fisher

docs/reference/api-v1.0.rst

@@ -24,15 +24,15 @@ Example Request:
 
     {
         "username": "test",
-        "password": "opensesame"
+        "password": "opensesame",
+        "email": "test@example.com"
     }
 
 Optional Parameters:
 
 .. code-block:: console
 
     {
-        "email": "test@example.com",
         "first_name": "test",
         "last_name": "testerson"
     }

docs/reference/api-v1.1.rst

@@ -38,15 +38,15 @@ Example Request:
 
     {
         "username": "test",
-        "password": "opensesame"
+        "password": "opensesame",
+        "email": "test@example.com"
     }
 
 Optional Parameters:
 
 .. code-block:: console
 
     {
-        "email": "test@example.com",
         "first_name": "test",
         "last_name": "testerson"
     }