next part of the docs and api documentation in beta ver

docs/api/fields/many-to-many.md

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+<a name="fields.many_to_many"></a>
+# fields.many\_to\_many
+
+<a name="fields.many_to_many.REF_PREFIX"></a>
+#### REF\_PREFIX
+
+<a name="fields.many_to_many.ManyToMany"></a>
+#### ManyToMany
+
+```python
+ManyToMany(to: Type["Model"], through: Type["Model"], *, name: str = None, unique: bool = False, virtual: bool = False, **kwargs: Any) -> Any
+```
+
+Despite a name it's a function that returns constructed ManyToManyField.
+This function is actually used in model declaration
+(as ormar.ManyToMany(ToModel, through=ThroughModel)).
+
+Accepts number of relation setting parameters as well as all BaseField ones.
+
+**Arguments**:
+
+- `to (Model class)`: target related ormar Model
+- `through (Model class)`: through model for m2m relation
+- `name (str)`: name of the database field - later called alias
+- `unique (bool)`: parameter passed to sqlalchemy.ForeignKey, unique flag
+- `virtual (bool)`: marks if relation is virtual.
+It is for reversed FK and auto generated FK on through model in Many2Many relations.
+- `kwargs (Any)`: all other args to be populated by BaseField
+
+**Returns**:
+
+`(ManyToManyField)`: ormar ManyToManyField with m2m relation to selected model
+
+<a name="fields.many_to_many.ManyToManyField"></a>
+## ManyToManyField Objects
+
+```python
+class ManyToManyField(ForeignKeyField,  ormar.QuerySetProtocol,  ormar.RelationProtocol)
+```
+
+Actual class returned from ManyToMany function call and stored in model_fields.
+
+<a name="fields.many_to_many.ManyToManyField.through"></a>
+#### through
+
+<a name="fields.many_to_many.ManyToManyField.default_target_field_name"></a>
+#### default\_target\_field\_name
+
+```python
+ | @classmethod
+ | default_target_field_name(cls) -> str
+```
+
+Returns default target model name on through model.
+
+**Returns**:
+
+`(str)`: name of the field
+