diff --git a/source/_docs/configuration/templating.markdown b/source/_docs/configuration/templating.markdown
index a62643977127..466c4ddcb34d 100644
--- a/source/_docs/configuration/templating.markdown
+++ b/source/_docs/configuration/templating.markdown
@@ -64,6 +64,7 @@ To improve the experience of writing Jinja templates, we have enabled the follow
 extensions:
 
 * [Loop Controls](https://jinja.palletsprojects.com/en/3.0.x/extensions/#loop-controls) (`break` and `continue`)
+* [Expression Statements](https://jinja.palletsprojects.com/en/3.0.x/templates/#expression-statement) (`do`)
 
 ## Home Assistant template extensions
 
@@ -991,6 +992,21 @@ To evaluate a response, go to **{% my developer_template title="Developer Tools
 
 {% endraw %}
 
+### Mutable dictionaries and lists
+
+- Filter `as_mutable` takes a list or dictionary and returns a mutable copy that you can modify using the standard Python methods and the [`do` syntax](https://jinja.palletsprojects.com/en/3.0.x/templates/#expression-statement).
+
+For example:
+
+{% raw %}
+
+```text
+{% set dict = {} | as_mutable %}
+{% do dict.update({"key": "value"}) %} {# dict now contains key->value #}
+```
+
+{% endraw %}
+
 ### Using templates with the MQTT integration
 
 The [MQTT integration](/integrations/mqtt/) relies heavily on templates. Templates are used to transform incoming payloads (value templates) to status updates or incoming service calls (command templates) to payloads that configure the MQTT device.