Add the description of the two nydusd binaries.

docs/containerd-env-setup.md

@@ -6,7 +6,7 @@ This document will walk through how to setup a nydus image service to work with
 
 Get `nydus-image`, `nydusd`, `nydusify`, `ctr-remote` and `nydus-overlayfs` binaries from [image-service release](https://github.com/dragonflyoss/image-service/releases/latest) page.
 
-`nydusd` currently has two binaries, `nydusd-fusedev` (for fuse daemon mode) and `nydusd-virtiofs` (for virtiofs daemon mode), chose the one that fits your mode and rename it `nydusd`.
+`nydusd` currently has two binaries, `nydusd-fusedev` (for fuse daemon mode) and `nydusd-virtiofs` (for virtiofs daemon mode), choose the one that fits your mode and rename it as `nydusd`.
 
 ```bash
 sudo cp nydusd nydus-image /usr/local/bin