SDK: Add a new Example plugin with documentation

.gitignore

AutoAnswer/CMakeLists.txt

Example/BotChatHandler.cpp

Example/BotChatHandler.h

Example/BotPeerChatSubscriber.cpp

Example/BotPeerChatSubscriber.h

Example/CMakeLists.txt

Example/ExampleAudioSubscriber.cpp

Example/ExampleMediaHandler.cpp

Example/ExampleVideoSubscriber.cpp

Example/data/locale/Example_en.json

Example/main.cpp

Example/manifest.json

SDK/Templates/CMakeLists.txt

build-plugin.py

build.md

contrib/build-dependencies.sh

daemon

docker/Dockerfile_ubuntu_20.04

extras/ci/android/Jenkinsfile