Fix link to wiki

Author: chad-iris

README.md

@@ -16,7 +16,7 @@ Solaris and Win32 environments.
 
 ## Documentation
 
-The [Wiki](https://github.com/iris-edu/libmseed/Wiki) provides an
+The [Wiki](https://github.com/iris-edu/libmseed/wiki) provides an
 overview of using the library. For function level documentation,
 man pages are included in the [doc](doc) directory.