Delete: delete grace and graceful from /cookbook/graceful-shutdown/

Author: sanposhiho

cookbook/graceful-shutdown/grace/server.go

@@ -14,16 +14,4 @@ description = "Graceful shutdown recipe for Echo"
 
 > Requires go1.8+
 
-## Using [grace](https://github.com/facebookgo/grace)
-
-`server.go`
-
-{{< embed "graceful-shutdown/grace/server.go" >}}
-
-## Using [graceful](https://github.com/tylerb/graceful)
-
-`server.go`
-
-{{< embed "graceful-shutdown/graceful/server.go" >}}
-
 ## [Source Code]({{< source "graceful-shutdown" >}})