Improve admin help message, includes videos tutorials

app/Resources/SonataAdminBundle/views/layout.html.twig

src/Biopen/CoreBundle/Admin/ConfigurationAPIAdmin.php

src/Biopen/CoreBundle/Admin/ConfigurationAdmin.php

src/Biopen/CoreBundle/Admin/ConfigurationFormAdmin.php

src/Biopen/CoreBundle/Admin/ConfigurationInfoBarAdmin.php

src/Biopen/CoreBundle/Admin/ConfigurationMailAdmin.php

src/Biopen/CoreBundle/Controller/CoreController.php

src/Biopen/CoreBundle/Resources/config/routing.yml

src/Biopen/GeoDirectoryBundle/Admin/ImportAbstractAdmin.php

src/Biopen/GeoDirectoryBundle/Admin/ImportAdmin.php

src/Biopen/GeoDirectoryBundle/Admin/ImportDynamicAdmin.php

...n/GeoDirectoryBundle/Controller/ElementFormController.php

...e/Resources/views/admin/blocks/block_monitoring.html.twig

...Bundle/Resources/views/admin/list/tree_category.html.twig

...le/Resources/views/admin/pages/bulks/bulk_index.html.twig

...irectoryBundle/Resources/views/admin/pages/help.html.twig

...s/views/admin/partials/show_element_form_fields.html.twig