Fix bullet points in aggregation framework reference documentation.

Closes: #3632

Author: petitcl

src/main/asciidoc/reference/mongodb.adoc

@@ -2444,9 +2444,8 @@ A `TypedAggregation`, just like an `Aggregation`, holds the instructions of the
 At runtime, field references get checked against the given input type, considering potential `@Field` annotations.
 [NOTE]
 ====
-Changed in 3.2 referencing none-xistent properties does no longer raise errors. To restore the previous behaviour use the `strictMapping` option of `AggregationOptions`.
+Changed in 3.2 referencing non-existent properties does no longer raise errors. To restore the previous behaviour use the `strictMapping` option of `AggregationOptions`.
 ====
-+
 * `AggregationDefinition`
 +
 An `AggregationDefinition` represents a MongoDB aggregation pipeline operation and describes the processing that should be performed in this aggregation step. Although you could manually create an `AggregationDefinition`, we recommend using the static factory methods provided by the `Aggregate` class to construct an `AggregateOperation`.