[doc] fix reference to ~src/cubes in tutorial
~src/cubes refer to the $HOME/cubes directory of "src" user while ~/src/cubes
refer to $HOME/src/cubes directory of current user.
Tutorials
~~~~~~~~~
We present a few tutorials of different levels. The blog building
tutorial introduces one smoothly to the basic concepts.
Then there is a photo gallery construction tutorial which highlights
more advanced concepts such as unit tests, security settings,
migration scripts.
.. toctree::
:maxdepth: 1
base/index
advanced/index
tools/windmill.rst
textreports/index
dataimport/index