Update how-to-contribute with gitbox
diff --git a/how-to-contribute.md b/how-to-contribute.md
index 0d16bb6..5db1ef4 100644
--- a/how-to-contribute.md
+++ b/how-to-contribute.md
@@ -117,7 +117,7 @@
You'll grab the Shiro source with git:
``` bash
-$ git clone https://git-wip-us.apache.org/repos/asf/shiro.git
+$ git clone https://gitbox.apache.org/repos/asf/shiro.git
```
If you already have the source, make sure you're working with the most recent version. Do a `git pull` if you cloned the source more than a few hours ago. (Apache Shiro development can move pretty fast!)
