v1.4.0 to fix HF bug

### Release v1.4.0

1. Fix TCB Clock bug in high frequencies. Check [Interrupt interval 2X requested interval #1](#1)
2. Add example to demo High Frequency
3. Delete Blynk-related examples
4. Add changelog.md

Author: khoih-prog

README.md

@@ -54,6 +54,7 @@
     * [3.1 TCB Clock Frequency 16MHz for highest accuracy](#31-tcb-clock-frequency-16mhz-for-highest-accuracy)
     * [3.2 TCB Clock Frequency 8MHz for very high accuracy](#32-tcb-clock-frequency-8mhz-for-very-high-accuracy)
     * [3.3 TCB Clock Frequency 250KHz for lower accuracy but longer time](#33-tcb-clock-frequency-250khz-for-lower-accuracy-but-longer-time)
+  * [4. Change_Interval on Arduino megaAVR Nano Every](#4-change_interval_HF-on-arduino-megaavr-nano-every)
 * [Debug](#debug)
 * [Troubleshooting](#troubleshooting)
 * [Issues](#issues)