diff --git a/lib/modules/datasource/custom/readme.md b/lib/modules/datasource/custom/readme.md
index 863d51800feaa5dc04333f9157cdc0270d1c7be6..b8e326cd4ef75993ef00dcc073bb1aa259a4d5ca 100644
--- a/lib/modules/datasource/custom/readme.md
+++ b/lib/modules/datasource/custom/readme.md
@@ -10,7 +10,7 @@ Options:
 | option                     | default | description                                                                                                                                                              |
 | -------------------------- | ------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
 | defaultRegistryUrlTemplate | ""      | URL used if no `registryUrl` is provided when looking up new releases                                                                                                    |
-| format                     | "json"  | format used by the API. Available values are: `json`, `plain`, `html`                                                                                                    |
+| format                     | "json"  | format used by the API. Available values are: `json`, `plain`, `yaml`, `html`                                                                                            |
 | transformTemplates         | []      | [JSONata rules](https://docs.jsonata.org/simple) to transform the API output. Each rule will be evaluated after another and the result will be used as input to the next |
 
 Available template variables:
@@ -119,7 +119,7 @@ When Renovate receives this response with the `plain` format, it will convert it
 
 After the conversion, any `jsonata` rules defined in the `transformTemplates` section will be applied as usual to further process the JSON data.
 
-### Yaml
+#### Yaml
 
 If `yaml` is used, response is parsed and converted into JSON for further processing.