Add documentation section about Filter and FilterDef

Description

Looks like we are missing the Filer and FilterDef section in the new User Guide.

Environment

None

Status

Assignee

Vlad Mihalcea

Reporter

Vlad Mihalcea

Fix versions

Labels

None

backPortable

None

Suitable for new contributors

None

Requires Release Note

None

Pull Request

None

backportDecision

None

Affects versions

5.1.0
5.0.9
5.2.1

Priority

Major
Configure