Update README.md.

quentinL92 · quentinL92 · commit a9eee266f179 · 2019-08-24T19:37:16.000Z
I went into your commits to see that it was actually not in the backend container but the nginx.
By the way, thank you for your amazing job.
diff --git a/documentation/docs/guide/nginx/README.md b/documentation/docs/guide/nginx/README.md
@@ -122,7 +122,7 @@ volumes:
   django-static:
 ```
 
-- Change the `build` section of the `backend` container:
+- Change the `build` section of the `nginx` container:
 
 ```yml
     build:
