add autocompletion files to contrib/

curl -o contrib/autocomplete.zsh https://raw.githubusercontent.com/urfave/cli/master/autocomplete/zsh_autocomplete
curl -o contrib/autocomplete.sh https://raw.githubusercontent.com/urfave/cli/master/autocomplete/bash_autocomplete

@@ -0,0 +84,4 @@
+
+	writer, err := os.Create(destPath)
+	if err != nil {
+		return err

@@ -34,1 +32,4 @@
+
+Shell completion can be added via `tea meta autocomplete --install`.
+
 ## Usage