Fix code block fences and typo.

Signed-off-by: Ding Fei <dingfei@stars.org.cn>

docs/extend/index.md

@@ -36,7 +36,7 @@ Hub or on a private registry.
 
 You install the plugin using a single command: `docker plugin install <PLUGIN>`.
 The `plugin install` command pulls the plugin from the Docker Hub or private
-registry. If necessary the CLI prompts you to accept any privilige requriements.
+registry. If necessary the CLI prompts you to accept any privilege requriements.
 For example the plugin may require access to a device on the host system.
 Finally it enables the plugin.
 
@@ -63,7 +63,7 @@ to create a volume.
     The plugin requests 2 privileges, the `CAP_SYS_ADMIN` capability to be able
     to do mount inside the plugin and `host networking`.
 
-2. Check for a value of `true` the `ENABLED` column to verify the plugin
+2.  Check for a value of `true` the `ENABLED` column to verify the plugin
 started without error.
 
     ```bash
@@ -73,7 +73,7 @@ started without error.
     vieux/sshfs         latest              true
     ```
 
-3. Create a volume using the plugin.
+3.  Create a volume using the plugin.
 
     ```bash
     $ docker volume create \
@@ -92,7 +92,7 @@ started without error.
     <content of /remote on machine 1.2.3.4>
     ```
 
-5. Verify the plugin successfully created the volume.
+5.  Verify the plugin successfully created the volume.
 
     ```bash
     $ docker volume ls

docs/extend/plugin_api.md

@@ -121,6 +121,7 @@ ExecStart=/usr/lib/docker/your-plugin
 WantedBy=multi-user.target
 ```
 The `socket` file (for example `/lib/systemd/system/your-plugin.socket`):
+
 ```
 [Unit]
 Description=Your plugin