feat(docs): import RS API documentation

src/content/docs/en/api/ad-spend-api/index.mdx

@@ -1,6 +1,6 @@
 ---
 title: "Partner ad spend push API"
-description: "Use the device API to view device information and clear device history from Adjust for testing purposes."
+description: "The Partner ad spend API allows you to send the advertising cost information associated with a campaign."
 category-title: Partner ad spend API
 slug: en/api/ad-spend-api/index
 ---

src/content/docs/en/api/partials/_RS-responses.mdx

@@ -0,0 +1,31 @@
+<ListTable>
+
+-  -  Response
+   -  Description
+   -  Notes
+-  -  `200`
+   -  Success
+   -  Returns report information
+-  -  `204`
+   -  No content
+   -  Returned if the response object is empty
+-  -  `400`
+   -  Bad request
+   -  Returned if your request is malformed or contains unsupported parameters
+-  -  `401`
+   -  Unauthorized
+   -  Returned if your credentials are incorrect or absent
+-  -  `403`
+   -  Forbidden
+   -  Returned if you try to access information you don't have permission to view
+-  -  `429`
+   -  Too many requests
+   -  Returned if you exceed 50 simultaneous requests
+-  -  `503`
+   -  Service unavailable
+   -  Returned if the server can't be reached
+-  -  `504`
+   -  Gateway timeout
+   -  Returned if the query takes too long to return a response
+
+</ListTable>

src/content/docs/en/api/rs-api/authentication.mdx

@@ -0,0 +1,13 @@
+---
+title: "Report service API authentication"
+description: "You need a bearer token to use the Report service API."
+slug: en/api/rs-api/authentication
+sidebar-position: 1
+sidebar-label: Authentication
+---
+
+import Authentication from "@content/en/api/partials/_Authentication.mdx";
+
+You need a [bearer token](https://developer.mozilla.org/en-US/docs/Web/HTTP/Authentication) to use the Report service API. You can get this token in the Adjust dashboard by following the steps in this article.
+
+<Authentication />