CSHARP-2976: Document How to do collations with LINQ.

Author: DmitryLukyanov

Docs/reference/content/reference/driver/crud/linq.md

@@ -69,6 +69,15 @@ var query = collection.AsQueryable()
 ]
 ```
 
+Also, there is a list of aggregate options that can be applied for the whole pipeline via [`AggregationOptions`]({{< apiref "T_MongoDB_Driver_AggregateOptions" >}}). Below is an example of configuring a [`Collation`]({{< docsref "reference/collation/" >}}):
+
+```csharp
+var collation = new Collation("en_US", strength: CollationStrength.Secondary);
+var aggregateOptions = new AggregateOptions { Collation = collation };
+var query = collection
+    .AsQueryable(aggregateOptions)
+    .Where(p => p.Name == "tom");
+```
 
 ### Stages