Update multi-platform.md

Fix typo and improves readability (with a simple comma).

Author: eabili0

content/manuals/build/building/multi-platform.md

@@ -65,8 +65,8 @@ The "classic" image store of the Docker Engine does not support multi-platform
 images. Switching to the containerd image store ensures that your Docker Engine
 can push, pull, and build multi-platform images.
 
-Creating a custom builder that uses the a driver with multi-platform support,
-such as the `docker-container` driver will let you build multi-platform images
+Creating a custom builder that uses a driver with multi-platform support,
+such as the `docker-container` driver, will let you build multi-platform images
 without switching to a different image store. However, you still won't be able
 to load the multi-platform images you build into your Docker Engine image
 store. But you can push them to a container registry directly with `docker