add pushd popd

doc/tutorials/introduction/windows_install/windows_install.markdown

@@ -67,7 +67,7 @@ else
     cd ..
 fi
 RepoSource=opencv
-cd Build/$RepoSource
+pushd Build/$RepoSource
 CMAKE_OPTIONS='-DBUILD_PERF_TESTS:BOOL=OFF -DBUILD_TESTS:BOOL=OFF -DBUILD_DOCS:BOOL=OFF  -DWITH_CUDA:BOOL=OFF -DBUILD_EXAMPLES:BOOL=OFF -DINSTALL_CREATE_DISTRIB=ON'
 cmake -G"$CMAKE_CONFIG_GENERATOR" $CMAKE_OPTIONS -DOPENCV_EXTRA_MODULES_PATH="$myRepo"/opencv_contrib/modules -DCMAKE_INSTALL_PREFIX="$myRepo"/install/"$RepoSource" "$myRepo/$RepoSource"
 echo "************************* $Source_DIR -->debug"
@@ -76,7 +76,7 @@ echo "************************* $Source_DIR -->release"
 cmake --build .  --config release
 cmake --build .  --target install --config release
 cmake --build .  --target install --config debug
-cd ..
+popd
 @endcode
     In this script I suppose you use VS 2015 in 64 bits
 @code{.bash}