update README.md

Signed-off-by: surenyi <surenyi82@163.com>

README.md

@@ -1,13 +1,17 @@
 1. Install driver
+```
     mkdir -p /lib/modules/`uname -r`/extra
     cp battery_drv.ko /lib/modules/`uname -r`/extra
     depmod -a
     echo battery_drv >> /etc/modules
+```
 
 2. Install service
-    sudo cp ttybattery.service to /etc/systemd/system
-    sudo chmod 0644 /etc/systemd/system/ttybattery.service
-    sudo systemctl enable ttybattery
-    sudo systemctl start ttybattery
-    sudo systemctl status ttybattery
+```
+    cp ttybattery.service to /etc/systemd/system
+    chmod 0644 /etc/systemd/system/ttybattery.service
+    systemctl enable ttybattery
+    systemctl start ttybattery
+    systemctl status ttybattery
+```