Updated base info about Fedora

install/linux/docker-ce/fedora.md

@@ -25,8 +25,8 @@ and distributions for different Docker editions, see
 
 To install Docker, you need the 64-bit version of one of these Fedora versions:
 
-- 28
-- 29
+- 30
+- 31
 
 ### Uninstall old versions
 
@@ -169,13 +169,20 @@ from the repository.
 
     Docker is installed but not started. The `docker` group is created, but no users are added to the group.
 
-3.  Start Docker.
+3.  Cgroups Exception
+    For Fedora 31, you'll have to enable the [backwards compatibility for Cgroups](https://fedoraproject.org/wiki/Common_F31_bugs#Other_software_issues).
+
+    ```bash
+    $ sudo grubby --update-kernel=ALL --args="systemd.unified_cgroup_hierarchy=0"
+    ```
+
+4.  Start Docker
 
     ```bash
     $ sudo systemctl start docker
     ```
 
-4.  Verify that Docker Engine - Community is installed correctly by running the `hello-world`
+5.  Verify that Docker Engine - Community is installed correctly by running the `hello-world`
     image.
 
     ```bash