doc: use ``` for embedded code

README.md

@@ -100,6 +100,7 @@ we will show a few choice examples here.
 
 Use the **LED** driver to toggle LEDs on the BBB:
 
+```go
 import "github.com/kidoman/embd"
 ...
 embd.InitLED()
@@ -108,20 +109,24 @@ Use the **LED** driver to toggle LEDs on the BBB:
 led, err := embd.NewLED(3)
 ...
 led.Toggle()
+```
 
 Even shorter when quickly trying things out:
 
+```go
 import "github.com/kidoman/embd"
 ...
 embd.InitLED()
 defer embd.CloseLED()
 ...
 embd.ToggleLED(3)
+```
 
 **3** is the same as **USR3** for all intents and purposes. The driver is smart enough to figure all this out.
 
 BBB + **PWM**:
 
+```go
 import "github.com/kidoman/embd"
 ...
 embd.InitGPIO()
@@ -131,9 +136,11 @@ BBB + **PWM**:
 defer pwm.Close()
 ...
 pwm.SetDuty(1000)
+```
 
 Control **GPIO** pins on the RaspberryPi / BeagleBone Black:
 
+```go
 import "github.com/kidoman/embd"
 ...
 embd.InitGPIO()
@@ -141,9 +148,11 @@ Control **GPIO** pins on the RaspberryPi / BeagleBone Black:
 ...
 embd.SetDirection(10, embd.Out)
 embd.DigitalWrite(10, embd.High)
+```
 
 Could also do:
 
+```go
 import "github.com/kidoman/embd"
 ...
 embd.InitGPIO()
@@ -153,9 +162,11 @@ Could also do:
 ...
 pin.SetDirection(embd.Out)
 pin.Write(embd.High)
+```
 
 Or read data from the **Bosch BMP085** barometric sensor:
 
+```go
 import "github.com/kidoman/embd"
 import "github.com/kidoman/embd/sensor/bmp085"
 ...
@@ -165,9 +176,11 @@ Or read data from the **Bosch BMP085** barometric sensor:
 ...
 temp, err := baro.Temperature()
 altitude, err := baro.Altitude()
+```
 
 Even find out the heading from the **LSM303** magnetometer:
 
+```go
 import "github.com/kidoman/embd"
 import "github.com/kidoman/embd/sensor/lsm303"
 ...
@@ -176,6 +189,7 @@ Even find out the heading from the **LSM303** magnetometer:
 mag := lsm303.New(bus)
 ...
 heading, err := mag.Heading()
+```
 
 The above two examples depend on **I2C** and therefore will work without change on almost all
 platforms.