Add docs.

Author: WaVEV

docs/releases/5.2.x.rst

@@ -10,7 +10,11 @@ Django MongoDB Backend 5.2.x
 New features
 ------------
 
-- ...
+- Added support for creating indexes from expressions.
+  Currently, only ``F()`` expressions are supported to reference top-level
+  model fields inside embedded models.
+
+
 
 Bug fixes
 ---------

docs/topics/indexes.md

@@ -0,0 +1,18 @@
+## Indexes from Expressions
+
+Django MongoDB Backend now supports creating indexes from expressions.
+Currently, only `F()` expressions are supported, which allows referencing
+fields from the top-level model inside embedded fields.
+
+Example:
+```python
+class Author(models.EmbeddedModel):
+    name = models.CharField()
+
+class Book(models.Model):
+    author = models.EmbeddedField(Author)
+
+    class Meta:
+        indexes = [
+            models.Index(F("author__name")),
+        ]