Modify Query Fields and Tags page for clarification

The Query Fields and Tags page is a mixture of conceptual information about the filter function and procedural information on fields and tags:
https://docs.influxdata.com/influxdb/cloud/query-data/flux/query-fields/

It would be better to move the filter() information to the filter() page:
https://docs.influxdata.com/flux/v0.x/stdlib/universe/filter/

Also, add an introductory paragraph at the top of Query Fields and Tags that covers essential query functions: From, Range, Filter. Include From() and Range().

New user feedback!
Page: https://docs.influxdata.com/influxdb/cloud/query-data/flux/query-fields/
Feedback: no data about ranges, not intuitive to use

Read the Query Fields and Tags page and the linked filter() documentation page. Move the filter() conceptual information to its page and add an introductory paragraph covering From, Range, and Filter; the work is done when the fields-and-tags page addresses ranges and essential query functions clearly.

Written by the indexing model from the issue text.