Merge pull request #446 from amplitude/user-privacy-api-concurrent-cost

Update user-privacy.md to include information about concurrent cost

content/collections/api/en/user-privacy.md

@@ -44,9 +44,9 @@ Using this API doesn't prevent future user tracking for the deleted users. To le
 
 ## Limits
 
-The endpoint `/api/2/deletions/users` has a rate limit of 1 HTTP request per second. Each HTTP request can contain up to 100 `amplitude_ids` or `user_ids`.
+The endpoint `/api/2/deletions/users` has a rate limit of 1 HTTP request per second. Each HTTP request can contain up to 100 `amplitude_ids` or `user_ids`. Additionally, there is a limit of 8 requests running in parallel for a given project. 
 
-Make up to 100 deletion requests per second if you batch 100 users in each request.
+Make up to 100 deletion requests per second if you batch 100 users in each request. 
 
 ## Delete users
 
@@ -757,4 +757,4 @@ A successful request returns a response with this schema:
 | ---- | ------------ |
 | 200  | Success      |
 | 400  | Bad Request  |
-| 401  | Unauthorized |
+| 401  | Unauthorized |