Update README.md
Fix -DBUILD_TESTING flag example.
@@ -238,7 +238,7 @@ make install
You may also want to compile the tests. In this case when you configure the project,
please call the following command
```
-cmake -DCMAKE_INSTALL_PREFIX:PATH=<custom-folder> -DBUILD_TESTING:ON ../
+cmake -DCMAKE_INSTALL_PREFIX:PATH=<custom-folder> -DBUILD_TESTING=ON ../
make
ctest
```
