add z submodule

.gitmodules

@@ -7,3 +7,7 @@
 [submodule "modules/completion/external"]
 	path = modules/completion/external
 	url = https://github.com/zsh-users/zsh-completions.git
+[submodule "modules/z/external"]
+	path = modules/z/external
+	url = https://github.com/rupa/z.git
+

modules/z/README.md

@@ -0,0 +1,14 @@
+z
+=
+
+Provides support for [z][1] ("jump around").
+
+Authors
+-------
+
+    -   [rupa][https://github.com/rupa]
+
+    -   [Ömer Yildiz][https://github.com/systemfreund]
+
+[1]: https://github.com/rupa/z
+

modules/z/external

@@ -0,0 +1 @@
+Subproject commit 6de41080cbcd208c5067c504d4572c24314e6123

modules/z/init.zsh

@@ -0,0 +1,2 @@
+# Source module files.
+source "${0:h}/external/z.sh"