Confusing warning/note for timestamp filter element

[dspigarelli]

The documentation for the timestamp filter element reads:

This setting is only used with the age filtertype, or
with the space filtertype if use_age is set to True.

This seems to be saying that timestamp should only be used with age or space (under certain conditions). However, timestamp is used in other filter types, including period. This is confusing and perhaps the wording could better reflect what's going on?

Expected Behavior

timestamp warning explains when it can be used in a way that doesn't preclude it from being used in filter types other than age and space

Actual Behavior

timestamp warning seems to suggest it should only be used with age and space, although other filter types such as period reference it.

Steps to Reproduce the Problem

1. Navigate to https://www.elastic.co/guide/en/elasticsearch/client/curator/current/fe_timestring.html and view the warning at the top of the document.

Specifications

• Version: 5.8
• Platform: All
• Subsystem: N/A

Context (Environment)

N/A

Detailed Description

Update the warning note for timestamp so it doesn't seem to preclude other filtertypes, such as period.