Merge pull request containerd#3836 from egernst/devmapper-docs-update

devmapper: update example base image size in README

snapshots/devmapper/README.md

@@ -15,7 +15,7 @@ Here's minimal sample entry that can be made in the configuration file:
   ...
   [plugins.devmapper]
     pool_name = "containerd-pool"
-    base_image_size = "128MB"
+    base_image_size = "8192MB"
   ...
 ```
 
@@ -39,4 +39,4 @@ ctr run --snapshotter devmapper docker.io/library/hello-world:latest test
 ## Requirements
 
 The devicemapper snapshotter requires `dmsetup` (>= 1.02.110) command line tool to be installed and
-available on your computer. On Ubuntu, it can be installed with `apt-get install dmsetup` command.
+available on your computer. On Ubuntu, it can be installed with `apt-get install dmsetup` command.