Doc improvements.

README.md

@@ -63,6 +63,8 @@ wiring details, pin names and hardware issues.
  5. [Hardware configuration](./README.md#5-hardware-configuration) How to write
  color_setup.py  
 
+#### [Device driver document.](./DRIVERS.md)
+
 # 1. Introduction
 
 This library provides a limited set of GUI objects (widgets) for displays whose
@@ -217,6 +219,8 @@ The `gui/core` directory contains the GUI core and its principal dependencies:
  compiling for other architectures may be found
  [here](https://github.com/peterhinch/micropython-font-to-py/blob/master/writer/WRITER.md#224-a-performance-boost).
 
+###### [Contents](./README.md#contents)
+
 ### 2.1.2 Demo scripts
 
 The `gui/demos` directory contains test/demo scripts.
@@ -249,6 +253,8 @@ import drivers.sharp.sharptest
 import drivers.sharp.clocktest
 ```
 
+###### [Contents](./README.md#contents)
+
 ### 2.1.3 Fonts
 
 Python font files are in the `gui/fonts` directory. The easiest way to conserve
@@ -299,6 +305,8 @@ Optional feature:
  * An STM32 implementation of
  [this optimisation](https://github.com/peterhinch/micropython-font-to-py/blob/master/writer/WRITER.md#224-a-performance-boost).
 
+###### [Contents](./README.md#contents)
+
 ### 2.2.1 Monochrome use
 
 A copy of the official driver for OLED displays using the SSD1306 chip is
@@ -791,9 +799,6 @@ If text is regularly appended to a `Textbox` its buffer grows, using RAM. The
 value of `ntrim` sets a limit to the number of lines which are retained, with
 the oldest (topmost) being discarded as required.
 
-###### [Contents](./README.md#contents)
-
-
 ###### [Contents](./README.md#contents)
 
 # 4. ESP8266
@@ -860,3 +865,5 @@ spi = machine.SPI(1)
 gc.collect()  # Precaution before instantiating framebuf
 ssd = SSD(spi, pcs, pdc, prst, height)  # Create a display instance
 ```
+
+###### [Contents](./README.md#contents)