x-pack/filebeat/docs/input: clarify interaction between split and cur…

…sor updates (#41384)

(cherry picked from commit cac5243)

x-pack/filebeat/docs/inputs/input-httpjson.asciidoc

@@ -783,6 +783,8 @@ Valid when used with `type: map`. When not empty, defines a new field where the
 
 If set to true, empty or missing value will be ignored and processing will pass on to the next nested split operation instead of failing with an error. Default: `false`.
 
+Note that if `ignore_empty_value` is `true` and the final result is empty, no event will be published, and no cursor update will be made. If a cursor update must be made for all responses, this should be set to `false` and the ingest pipeline must be configured to tolerate empty event sets.
+
 [float]
 ==== `response.split[].split`
 
@@ -1556,6 +1558,8 @@ See  <<chain-step-replace_with, chain[].step.replace_with>> .
 
 Cursor is a list of key value objects where arbitrary values are defined. The values are interpreted as  <<value-templates,value templates>> and a default template can be set. Cursor state is kept between input restarts and updated once all the events for a request are published.
 
+If no event is published, no cursor update is made. This can have implications on how cursor updates should be performed when the target API returns empty response sets.
+
 Each cursor entry is formed by:
 
 - A `value` template, which will define the value to store when evaluated.