move mic example to audio subfolder

diff --git a/examples/mic/Makefile b/examples/audio/mic/Makefile
similarity index 100%
rename from examples/mic/Makefile
rename to examples/audio/mic/Makefile

diff --git a/examples/mic/README.md b/examples/audio/mic/README.md
similarity index 100%
rename from examples/mic/README.md
rename to examples/audio/mic/README.md

diff --git a/examples/mic/source/main.c b/examples/audio/mic/source/main.c
similarity index 100%
rename from examples/mic/source/main.c
rename to examples/audio/mic/source/main.c