Visual builder aggregation help reference

[tbragin]

In Visualize, we typically expose Elasticsearch terminology around which aggregations we're using (e.g. Terms). One notable exception is "Unique Count", which is actually fulfilled by the cardinality aggregation in Elasticsearch. Either way, users get confused -- some don't know what "Terms" refers to, others would really like to know how unique count is calculated.

Proposal is to provide a reference in Visualize to help the user know more about the aggregation they are choosing.

Some ideas:

• Could selector itself supports basic help text?
• Once the aggregation is chosen, show a tooltip with more info and a link to ES aggregation reference

[sophiec20]

Also concerns ML. We have a function distinct count which effectively maps to unique count which are both approximations, albeit slightly different ones.

We currently have a mix of labelling in the ML UI - which is not ideal. I am curious why unique count is used as I feel that the concept is more commonly referred to as distinct e.g. even in our own documentation..

A single-value metrics aggregation that calculates an approximate count of distinct values.

Also, off the topic of this GitHub issue (but not the one that brought me here #7955), perhaps Average should be renamed to Mean, especially now that we have a Median.

[timroes]

We nowadays have help links for all aggregations in the editor, so you can directly jump to the documentation for more explanation. With the new visual editor (#17076), we are trying to get rid of Elasticsearch specific terminology more and rather use common names. I would be closing this issue, since now that we have the links available there are no current plans for improving that behavior in the existing editor.