release: update CHANGELOG with 0.3.0 release info

Signed-off-by: Ron Evans <ron@hybridgroup.com>

CHANGELOG.md

@@ -1,3 +1,29 @@
+0.3.0
+---
+- **new devices**
+    - Buzzer for piezo or small speaker
+    - PDM MEMS microphone support using I2S interface
+- **enhancements**
+    - epd2in13: added rotation
+    - espat
+        - add built-in support for MQTT publish using the Paho library packets, alongside some modifications needed for the AT protocol.
+        - add DialTLS and Dial methods, update MQTT example to allow both MQTT and MQTTS connections
+        - add example that uses MQTT publish to open server
+        - add README with information on how to flash ESP32 or ESP8266 with AT command set firmware.
+        - add ResolveUDPAddr and ResolveTCPAddr implementations using AT command for DNS lookup
+        - change Response() method to use a passed-in timeout value instead of fixed pauses.
+        - implement TCPConn using AT command set
+        - improve error handling for key TCP functions
+        - refactor net and tls interface compatible code into separate sub-packages
+        - update MQTT example for greater stability
+        - use only AT commands that work on both ESP8266 and ESP32
+        - add documentation on how to use Arduino Nano33 IoT built-in WiFi NINA-W102 chip.
+- **bugfixes**
+    - core: Error strings should not be capitalized (unless beginning with proper nouns or acronyms) or end with punctuation, since they are usually printed following other context.
+    - docs: add note to current/future contributors to please start by opening a GH issue to avoid duplication of efforts
+    - examples: typo in package name of examples
+    - mpu6050: properly scale the outputs of the accel/gyro
+
 0.2.0
 ---
 - **new devices**