Update the Readme

Author: mcauser

README.md

@@ -1,34 +1,56 @@
 lcd and i2c_lcd
 ===============
 
-Python code for talking to character based LCDs.
-
-The I2c_Lcd class allows for talking to i2c based LCDs. There are also variants
-of the code for MicroPython. All of the files which start with pyb were tested
-on the pyboard.
+Python code for talking to HD44780 compatible character based dot matrix LCDs.
+
+You can communicate with the LCDs using either 4 or 8 GPIO pins.
+
+Alternatively, the I2C classes implement 8-bit GPIO expander boards
+[PCF8574](http://www.ti.com/lit/ds/symlink/pcf8574.pdf) and
+[MCP23008](http://www.microchip.com/wwwproducts/en/MCP23008)
+which reduces the number of required GPIO pins to two (SCL, SDA).
+The boards usually mount behind the LCDs and are commonly called "backpacks".
+
+The most commonly used display is a "1602" or "16x2", which features 16 columns
+and 2 rows of characters. There are also other LCDs using the same HD44780
+controller. eg. 8x2, 16x1, 16x4, 20x2, 20x4, 40x1, 40x2. Each come in various
+backlight and pixel colours.
+
+There are also variants of the code for [MicroPython](http://micropython.org/).
+All of the files which start with **pyb_** were tested on the
+[pyboard](https://store.micropython.org/store/#/products/PYBv1_1).
+Files starting with **esp8266_** were tested on a
+[WeMos D1 Mini](https://www.wemos.cc/product/d1-mini.html).
+Files starting with **nodemcu_** were tested on a
+[NodeMCU development board](https://en.wikipedia.org/wiki/NodeMCU).
+The files containing **adafruit_lcd** were tested on an Adafruit
+[I2C / SPI character LCD backpack](https://www.adafruit.com/product/292)
 
 Files
 =====
 
 | File                          | Description                           |
 | -----                         | -----------                           |
+| esp8266_i2c_lcd.py            | ESP8266 PCF8574 I2C HAL               |
+| esp8266_i2c_lcd_test.py       | ESP8266 test using PCF8574 backpack   |
+| i2c_lcd.pyb                   | Linux PCF8574 I2C HAL                 |
+| i2c_lcd_test.pyb              | Linux test using PCF8574 backpack     |
 | lcd.py                        | Core logic                            |
-| i2c_lcd.pyb                   | Linux I2C HAL                         |
+| nodemcu_gpio_lcd.py           | NodeMCU GPIO HAL                      |
+| nodemcu_gpio_lcd_test.py      | NodeMCU test using 4-bit GPIO         |
 | pyb_gpio_lcd.py               | Pyboard GPIO HAL                      |
 | pyb_gpio_lcd_test8.py         | Pyboard test using 8-bit GPIO         |
 | pyb_gpio_lcd_test.py          | Pyboard test using 4-bit GPIO         |
-| pyb_i2c_adafruit_lcd.py       | Pyboard I2C HAL for Adafruit backpack |
-| pyb_i2c_adafruit_lcd_test.py  | Test for Adafruit backpack            |
-| pyb_i2c_lcd.py                | Pyboard I2C HAL for PCF8574 backpack  |
-| pyb_i2c_lcd_test.py           | Test for PCF8574 backpack             |
-| nodemcu_gpio_lcd.py           | NodeMCU GPIO HAL                      |
-| nodemcu_gpio_lcd_test.py      | NodeMCU test using 4-bit GPIO         |
+| pyb_i2c_adafruit_lcd.py       | Pyboard MCP23008 I2C HAL              |
+| pyb_i2c_adafruit_lcd_test.py  | Pyboard test using Adafruit backpack  |
+| pyb_i2c_lcd.py                | Pyboard PCF8574 I2C HAL               |
+| pyb_i2c_lcd_test.py           | Pyboard test using PCF8574 backpack   |
 
 
-The files which end in _test.py are examples which show how the corresponding
+The files which end in **_test.py** are examples which show how the corresponding
 file is used.
 
-i2c_lcd.py was tested on a BeagleBone Black using a 2 x 16 LCD with an i2c
+**i2c_lcd.py** was tested on a [BeagleBone Black](https://beagleboard.org/black) using a 2 x 16 LCD with an I2C
 module similar to [this one](http://arduino-info.wikispaces.com/LCD-Blue-I2C).
 
 This code was adapted from some C code that I had written previously for