adds -d

 thanks to moby/moby#2838

service/README.md

@@ -7,7 +7,7 @@
 
 **run the container, binding container port 5000 to your preferred local port:**
 
-`docker run -p 5000:5000 fleapday`
+`docker run -p 5000:5000 -d fleapday`
 
 Access the running container on http://127.0.0.1:5000 (or `docker-machine ip <machine>`)
 
@@ -31,4 +31,4 @@ valid routes include:
 * `/ping`: health check
 * `/is-leap-year/<year>`: will verify that the provided year is in fact a leap year
 * `/get-all-leap-years`: returns a list of leap years between 1752 and 2019
-* `/get-leap-day/<year>`: checks if the provided `<year>` is a leap year, if so returns a human readable day of the week for `02-29-<year>`
+* `/get-leap-day/<year>`: checks if the provided `<year>` is a leap year, if so returns a human readable day of the week for `02-29-<year>`