docs: Add links to LCD and AMP skin schematics.

docs/hardware/index.rst

+.. _hardware_index:
+
 The pyboard hardware
 ====================
 
+For the pyboard:
+
 * `PYBv1.0 schematics and layout <http://micropython.org/resources/PYBv10b.pdf>`_ (2.4MiB PDF)
 * `PYBv1.0 metric dimensions <http://micropython.org/resources/PYBv10b-metric-dimensions.pdf>`_ (360KiB PDF)
 * `PYBv1.0 imperial dimensions <http://micropython.org/resources/PYBv10b-imperial-dimensions.pdf>`_ (360KiB PDF)
 
+For the official skin modules:
+
+* `LCD32MKv1.0 schematics <http://micropython.org/resources/LCD32MKv10-schematics.pdf>`_ (194KiB PDF)
+* `AMPv1.0 schematics <http://micropython.org/resources/AMPv10-schematics.pdf>`_ (209KiB PDF)
+
 Datasheets for the components on the pyboard
 ============================================
 

docs/tutorial/amp_skin.rst

@@ -17,6 +17,8 @@ The following video shows how to solder the headers, microphone and speaker onto
 
     <iframe style="margin-left:3em;" width="560" height="315" src="http://www.youtube.com/embed/fjB1DuZRveo?rel=0" frameborder="0" allowfullscreen></iframe>
 
+For circuit schematics and datasheets for the components on the skin see :ref:`hardware_index`.
+
 Example code
 ------------
 

docs/tutorial/lcd_skin.rst

@@ -18,6 +18,8 @@ At the end of the video, it shows you how to correctly connect the LCD skin to t
 
     <iframe style="margin-left:3em;" width="560" height="315" src="http://www.youtube.com/embed/PowCzdLYbFM?rel=0" frameborder="0" allowfullscreen></iframe>
 
+For circuit schematics and datasheets for the components on the skin see :ref:`hardware_index`.
+
 Using the LCD
 -------------