Update notebook links to point to nbviewer.

Build/NucleoTNC.ipynb

@@ -6,7 +6,7 @@
    "source": [
     "# Nucleo TNC\n",
     "\n",
-    "The Nucleo TNC is a breadboard implementation of the [Mobilinkd TNC3](https://store.mobilinkd.com/collections/frontpage/products/mobilinkd-tnc3) using a STM32L432KC Nucleo32 board.  This TNC faithfully implements the audio section and EEPROM storage of the TNC3.  It omits the battery charging and Bluetooth components of the TNC3.  It presents as a KISS TNC over a USB serial port.\n",
+    "The Nucleo TNC is a breadboard implementation of the [Mobilinkd TNC3](https://store.mobilinkd.com/products/mobilinkd-tnc3) using a STM32L432KC Nucleo32 board.  This TNC faithfully implements the audio section and EEPROM storage of the TNC3.  It omits the battery charging and Bluetooth components of the TNC3.  It presents as a KISS TNC over a USB serial port.\n",
     "\n",
     "The Nucleo TNC is a 1200 baud KISS TNC built using an inexpensive microcontroller board with great digital signal processing capabilities and very low power consumption. It's an open implementation of our commercial product, the TNC3, designed to encourage experimentation and learning in electronics and software engineering. It's a more advanced version of a [similar project we designed for the Arduino Nano](http://www.mobilinkd.com/2014/09/11/arduino-kiss-tnc/), which was based on our TNC1/TNC2 product.\n",
     "\n",
@@ -16,7 +16,7 @@
     "\n",
     "This project is intended for amateur radio operators from beginners to advanced.  If you want to just dive in to building it without understanding the theory of operations, start at the overview and skip to the BOM and Assembly Instructions.  For those who wish to understand the theory of operation from an electrical perspective, we start with the *Schematic* and *Theory of Operation* sections after a brief overview.\n",
     "\n",
-    "And for those who wish to understand the digital signal processing involved in this project, please refer to the [AFSK Demodulator](https://github.com/mobilinkd/afsk-demodulator/blob/master/afsk-demodulator.ipynb) tutorial which outlines the basics of how the demodulator is constructed.  You can also refer to the source repository for the firmware.\n",
+    "And for those who wish to understand the digital signal processing involved in this project, please refer to the [AFSK Demodulator](https://nbviewer.jupyter.org/github/mobilinkd/afsk-demodulator/blob/master/afsk-demodulator.ipynb) tutorial which outlines the basics of how the demodulator is constructed.  You can also refer to the source repository for the firmware.\n",
     "\n",
     "This breadboard TNC has the same radio interface pinout as the Mobilinkd TNCs and is designed to be used with the same cables as a Mobilinkd TNC.  Pre-made cables for your radio can be purchased at http://store.mobilinkd.com or you can make your own.\n",
     "\n",