v1.4.0 to save heap when sending large data

### Releases v1.4.0

1. Support using `CString` in optional `SDRAM` to save heap to send `very large data`. Check [request->send(200, textPlainStr, jsonChartDataCharStr); - Without using String Class - to save heap #8](#8)
2. Add multiple examples to demo the new feature

library.properties

@@ -1,5 +1,5 @@
 name=Portenta_H7_AsyncWebServer
-version=1.3.0
+version=1.4.0
 author=Hristo Gochkov,Khoi Hoang
 maintainer=Khoi Hoang <khoih.prog@gmail.com>
 sentence=Asynchronous WebServer Library for STM32H7-based Portenta_H7 using mbed_portenta core.