Move 'examples/coap-example' to 'examples/coap'

examples/coap/Makefile

examples/coap/README.md

examples/coap/coap-example-client.c

examples/coap/coap-example-observe-client.c

examples/coap/coap-example-server.c

examples/coap/in6addr.patch

examples/coap/plugtest-server.c

examples/coap/plugtest.h

examples/coap/project-conf.h

examples/coap/resources/res-b1-sep-b2.c

examples/coap/resources/res-battery.c

examples/coap/resources/res-chunks.c

examples/coap/resources/res-event.c

examples/coap/resources/res-hello.c

examples/coap/resources/res-leds.c

examples/coap/resources/res-light.c

examples/coap/resources/res-mirror.c

examples/coap/resources/res-plugtest-create1.c

examples/coap/resources/res-plugtest-create2.c

examples/coap/resources/res-plugtest-create3.c