Rtos API example

Revision:
0:9fca2b23d0ba
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-os/features/netsocket/mbed_lib.json	Sat Feb 23 12:13:36 2019 +0000
@@ -0,0 +1,6 @@
+{
+    "name": "nsapi",
+    "config": {
+        "present": 1
+    }
+}