Fix typo - OpenAPI link reference(yaml -> json) (#3124)

Author: vst-name

reference/api/overview.mdx

@@ -11,7 +11,7 @@ If you are new to Meilisearch, check out the [getting started](/learn/self_hoste
 
 ### OpenAPI
 
-You can get the [Meilisearch OpenAPI specifications here](https://github.com/meilisearch/open-api/blob/main/open-api.yaml).
+You can get the [Meilisearch OpenAPI specifications here](https://github.com/meilisearch/open-api/blob/main/open-api.json).
 
 ## Document conventions