Reduce example surface to Lightweight MQTT examples (#80)

Author: gguuss

README.md

@@ -26,10 +26,7 @@ Currently, we support the following hardware targets:
 Some examples use specific dependencies that need to be installed via the Arduino Library manager.
 
 * [rBase64](https://github.com/boseji/rBASE64) - Used when encoding `binary_data` payloads
-* [Buffered Streams](https://github.com/paulo-raca/ArduinoBufferedStreams) - Buffer for PubSub MQTT Client
 * [lwMQTT](https://github.com/256dpi/arduino-mqtt) - Used in MQTT Esp8266 example
-* [PubSub Client](https://github.com/knolleary/pubsubclient) - Used in MQTT for Esp32
-* [ThingPulse OLED SSD1306](https://github.com/ThingPulse/esp8266-oled-ssd1306) - Used in Esp32-ssd1306
 
 ## Quickstart