make reference to tail function

As an alternative to the sort and limit function, tail function should be mentioned here also.
typical query where tail function without sort is way more performant:
“get latest xx values within a timerange”
using
|> tail(n: 10000)
is much faster then the suggested solution in the current doc.
|> sort(columns: ["_time"], desc: **true**)
|> limit(n: 10000)

##### Relevant URLs
- https://docs.influxdata.com/influxdb/v2.4/query-data/flux/sort-limit/
- salesforce support case: #00107489 - poor performance on certain queries [ ref:_00D37JQwH._5001S1YiY5U:ref ]

Start by reading the sort-limit documentation at the relevant URL and compare its suggested sort and limit query with the issue's tail example. Done means the page mentions tail as an alternative for retrieving the latest values within a time range and includes the supplied query context.

Written by the indexing model from the issue text.