sh: Add serve alias to create a quick file server

Quickly put up a file server in the current directory by typing `serve`
and the rest is figured out automatically.

Makes use of `sfz`, `gossa`, `rossa` in that order to set up the file
server.

sh/.config/sh/alias.d/sfz.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env sh
+## Quickly bring up a file server for
+#  the current directory.
+
+if exist sfz; then
+	alias serve="sfz"
+elif exist gossa; then
+	alias serve="gossa"
+elif exist rossa; then
+	alias serve="rossa"
+fi