Monggregate

Docs

* Completed documentation by adding a page on how to use search features

Fixes

* Fixes bug preventing from using faceted search
* Fixes search crashing with some mismatch between keyword arguments and operators

Fixes

* Fixed build that has failed on the last two versions (0.18.0, 0.19.0)

Fixes

* Fixed bug preventing to use `Compound` operator with `Search` and `SearchMeta` classes.

New Features

* Pipelinized `Search` and `SearchMeta` classes. That is complex expressions can be built step by step by chaining operators.
* Updated `search` method in `¨Pipeline` class to ease the use of the search stages.
* Clarified and simplified faceted search

Refactoring

* Use operators rather than statement in `Compound` class
* Factorized `Search` and `SearchMeta` classes by creating a `SearchBase` class
* Use `CountOptions` rather than raw dicts
* Created `AnyStage` union type

Docs

* Spelling and grammar fixes

**Docs**
* First version of the documentation 🍾 !

**[Fixes](https://github.com/VianneyMI/monggregate/blob/main/changelog.md#fixes)**

* Allow to use iterable and dicts to group by in Group class and pipeline group function

**Fixes**

- Fixed replace_root by passing document argument to ReplaceRoot class