splitting the getting started page

docs/getting-started/buttons.md

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+# Button A and button B
+
+### ~avatar avatar
+
+Buttons are great to build games!
+
+### ~
+
+This program will show the word **ANTEATER** on the LED
+screen when you press button `A`.
+
+```blocks
+input.onButtonPressed(Button.A, () => {
+    basic.showString("ANTEATER");
+});
+```
+
+#### ~hint
+
+The ``showString`` block can show letters, numbers, and punctuation
+on the micro:bit screen.
+
+#### ~
+
+Now try to unscramble these blocks in the editor so that the micro:bit
+shows **BANANA** when you press button `B`.
+
+```shuffle
+input.onButtonPressed(Button.B, () => {
+    basic.showString("BANANA");
+});
+```
+#### ~hint
+
+You can find the letter `B` by clicking the letter `A` on the
+``onButtonPressed`` block.
+
+#### ~
+
+Click **Compile** to move your program to the BBC micro:bit!
+
+#### Your turn!
+
+Can you combine these blocks so your program shows your real name
+instead of **ANTEATER** when you press `A`, but _your secret agent
+name_ instead of **BANANA** when you press `B`?
+
+### Pins
+
+You can also use the pins as buttons.  (The pins are the holes in the
+metal stripe at the bottom of the micro:bit board.)  For example, hold
+the ``GND`` button with one hand and touch the ``0`` pin (called
+``P0``) with your other hand to tell the micro:bit you're pressing it.
+
+Unscramble the blocks in the editor to show a heart when you touch
+pin ``P0``.
+
+```shuffle
+input.onPinPressed(TouchPin.P0, () => {
+    basic.showLeds(`
+. # . # .
+# . # . #
+# . . . #
+. # . # .
+. . # . .`);
+});
+```
+Click **Compile** to move your program to the BBC micro:bit!
+
+## ~hint
+
+Try this experiment: find a friend and hold hands. Touch the ``GND``
+pin while your friend presses the ``P0`` pin. You should see the
+heart! The electric current is going through your bodies and across
+your handshake to make it happen!
+
+## ~
+
+## [NEXT: SHAKE](/getting-started/shake)