mkfifo: add usage examples (#13488)

Co-authored-by: spageektti <git@spageektti.cc>

pages/common/mkfifo.md

@@ -6,3 +6,11 @@
 - Create a named pipe at a given path:
 
 `mkfifo {{path/to/pipe}}`
+
+- Send data through a named pipe and send the command to the background:
+
+`echo {{"Hello World"}} > {{path/to/pipe}} &`
+
+- Receive data through a named pipe:
+
+`cat {{path/to/pipe}}`