feat: document search result set limits

Author: alnr

docs/kratos/manage-identities/search/identity-search-api.mdx

@@ -105,6 +105,13 @@ possible.
 
 :::
 
+## Result set limits
+
+The identity search API is not a replacement for the [List Identities API](/reference/api#tag/identity/operation/listIdentities).
+Unlike the List Identities API, the search API does not support pagination and will return a maximum of 1,000 results per request.
+To paginate through _all_ your identities, use the [List Identities API](/reference/api#tag/identity/operation/listIdentities). If
+you find you are frequently hitting this limit, consider refining your search queries to reduce the number of results returned.
+
 ## Consistency and availability
 
 The search index powering advanced identity search is eventually consistent with the main identity store. This means that there