Added / corrected README files for the SPI master / slave examples under peripherals

Author: krzychb

examples/peripherals/spi_master/README.md

@@ -0,0 +1,5 @@
+## SPI master example
+
+This code displays a simple graphics with varying pixel colors on the 320x240 LCD on an ESP-WROVER-KIT board.
+
+If you like to adopt this example to another type of display or pinout, check [manin/spi_master_example_main.c] for comments that explain some of implementation details.

examples/peripherals/spi_slave/README.md

@@ -1,22 +1,15 @@
 ## SPI slave example
 
-These two projects illustrate the SPI Slave driver. They're supposed to be flashed into two separate ESP32s connected to
-eachother using the SPI pins defined in app_main.c. Once connected and flashed, they will use the spi master and spi slave
-driver to communicate with eachother. The example also includes a handshaking line to allow the master to only poll the 
-slave when it is actually ready to parse a transaction.
+These two projects illustrate the SPI Slave driver. They're supposed to be flashed into two separate ESP32s connected to eachother using the SPI pins defined in app_main.c. Once connected and flashed, they will use the spi master and spi slave driver to communicate with eachother. The example also includes a handshaking line to allow the master to only poll the  slave when it is actually ready to parse a transaction.
 
 Please run wires between the following GPIOs between the slave and master to make the example function:
 
-========= ====== =======
-Signal    Slave  Master
-========= ====== =======
-Handshake GPIO2  GPIO2
-MOSI      GPIO12 GPIO12
-MISO      GPIO13 GPIO13
-SCLK      GPIO15 GPIO15
-CS        GPIO14 GPIO14
-========= ====== =======
+| Signal    | Slave  | Master |
+|-----------|--------|--------|
+| Handshake | GPIO2  | GPIO2  |
+| MOSI      | GPIO12 | GPIO12 |
+| MISO      | GPIO13 | GPIO13 |
+| SCLK      | GPIO15 | GPIO15 |
+| CS        | GPIO14 | GPIO14 |
 
-Be aware that the example by default uses lines normally reserved for JTAG. If this is an issue, either because of hardwired
-JTAG hardware or because of the need to do JTAG debugging, feel free to change the GPIO settings by editing defines in the top
-of main.c in the master/slave source code.
+Be aware that the example by default uses lines normally reserved for JTAG. If this is an issue, either because of hardwired JTAG hardware or because of the need to do JTAG debugging, feel free to change the GPIO settings by editing defines in the top of main.c in the master/slave source code.