Update readme file

Signed-off-by: fpr <fabien.perroquin@wi6labs.com>

README.md

@@ -1,2 +1,37 @@
 # MX25R6435F
 Arduino library to support the Quad-SPI NOR Flash memory MX25R6435F
+
+## API
+
+The library provides the following API:
+
+* begin()
+* end()
+* write()
+* read()
+* mapped()
+* erase()
+* eraseChip()
+* eraseSector()
+* suspendErase()
+* resumeErase()
+* sleep()
+* wakeup()
+* status()
+* info()
+* length()
+
+## Examples
+
+3 sketches provide basic examples to show how to use the library API.  
+demo.ino uses basic read/write functions.  
+eraseChip.ino erases all data present in the memory.  
+memoryMappedMode.ino shows how to use the mapped mode.  
+
+## Documentation
+
+You can find the source files at  
+https://github.com/stm32duino/MX25R6435F
+
+The MX25R6435F datasheet is available at  
+http://www.mxic.com.tw/Lists/Datasheet/Attachments/6270/MX25R6435F,%20Wide%20Range,%2064Mb,%20v1.4.pdf