Merge pull request #1153 from BSWANG/patch-1

optimize  selectadriver.md

engine/userguide/storagedriver/selectadriver.md

@@ -63,7 +63,7 @@ plan to use for your Docker host's local storage area. Some storage drivers can
 drivers require the backing filesystem to be the same as the storage driver.
 For example, the `btrfs` storage driver on a Btrfs backing filesystem. The
 following table lists each storage driver and whether it must match the host's
-backing file system:
+backing filesystem:
 
 |Storage driver |Commonly used on |Disabled on                                         |
 |---------------|-----------------|----------------------------------------------------|
@@ -218,4 +218,4 @@ on `overlay`. For users with at least a 4.0 kernel and no existing or required
 * [Understand images, containers, and storage drivers](imagesandcontainers.md)
 * [AUFS storage driver in practice](aufs-driver.md)
 * [Btrfs storage driver in practice](btrfs-driver.md)
-* [Device Mapper storage driver in practice](device-mapper-driver.md)
+* [Device Mapper storage driver in practice](device-mapper-driver.md)