zephyr/README: Reorder content related to recently added I2C.

So it fits better with existing narrative.

ports/zephyr/README.md

@@ -12,8 +12,8 @@ Features supported at this time:
 
 * REPL (interactive prompt) over Zephyr UART console.
 * `utime` module for time measurements and delays.
-* `machine.I2C` class for I2C control.
 * `machine.Pin` class for GPIO control.
+* `machine.I2C` class for I2C control.
 * `usocket` module for networking (IPv4/IPv6).
 * "Frozen modules" support to allow to bundle Python modules together
   with firmware. Including complete applications, including with
@@ -82,13 +82,6 @@ To blink an LED:
         LED.value(0)
         time.sleep(0.5)
 
-To scan for I2C slaves:
-
-    from machine import I2C
-
-    i2c = I2C("I2C_0")
-    i2c.scan()
-
 The above code uses an LED location for a FRDM-K64F board (port B, pin 21;
 following Zephyr conventions port are identified by "GPIO_x", where *x*
 starts from 0). You will need to adjust it for another board (using board's
@@ -96,6 +89,13 @@ reference materials). To execute the above sample, copy it to clipboard, in
 MicroPython REPL enter "paste mode" using Ctrl+E, paste clipboard, press
 Ctrl+D to finish paste mode and start execution.
 
+Example of using I2C to scan for I2C slaves:
+
+    from machine import I2C
+
+    i2c = I2C("I2C_0")
+    i2c.scan()
+
 
 Minimal build
 -------------