updated structure

``build log`` explained

-----------------------

The build log includes several sections on

The build log includes 6 sections.

1. a check on versions of requirements

Check on versions of requirements

   The status will be non-zero if any of your requirements is behind other developers.

2. a check on installation of requirements

Check on installation of requirements

   The status will be non-zero if ``pip install -r requirements.txt`` exit with non-zero status.

3. a check on installation of package

Check on installation of package

   The status will be non-zero if the following code are unsuccessfully executed

   .. code-block:: bash

      python setup.py sdist                                 # build source code

      pip install dist/*.tar.gz --force-reinstall --no-deps # install package without dependencies

4. a check on import of interfaces (top_level_interface)

Check on import of interfaces (``top_level_interface``)

   The status will be non-zero if the following code are unsuccessfully executed

   .. code-block:: python

      from <your_package>.top_level_interface import *

5. unit tests and coverage

Run unit tests and coverage

   The status will be non-zero if the following code are unsuccessfully executed

   .. code-block:: bash

      coverage run -m pytest --import-mode=importlib

6. Numpydoc validation of interfaces

``Numpydoc`` validation of interfaces

   .. code-block:: bash