Add readme for daemon directory

See issue #5873

Docker-DCO-1.1-Signed-off-by: Timothy <timothyhobbs@seznam.cz> (github: https://github.com/timthelion)

daemon/README.md

@@ -0,0 +1,10 @@
+This directory contains code pertaining to running containers and storing images
+
+Code pertaining to running containers:
+
+ - execdriver
+ - networkdriver
+
+Code pertaining to storing images:
+
+ - graphdriver