[DOCS] Reporting and sharing: Mention impact of selected time ranges

User feedback:

[Reporting and sharing](https://www.elastic.co/guide/en/kibana/current/reporting-getting-started.html) -> "When sharing a snapshot, the current relative time range filter is on. I wanted to know how to share a snapshot with the time range also \"snapped\". I.e. so I don't share it, and no results because \"15 minutes back\" filter is being applied. Seems this is very common for troubleshooting and sharing logs, shouldn't this be very easy? Thanks."