Fix typo in README.md

README.md

@@ -99,7 +99,6 @@ E.g. if you want to build the sources' directory structure as follows
 .
 ├── exple-cmake-build
 │   └── exple-cmake-build
-│       └── exple-cmake-build
 ├── explelibx-common
 │   └── explelibx-common
 └── explelibx-mgrid