- added guide to add components & site components

dev/docs/frontend/core/setup.md

dev/docs/frontend/overview/innerStructure.md

dev/docs/frontend/overview/workflow.md

dev/docs/frontend/tutorials/components.md

dev/docs/frontend/tutorials/readme.md

dev/docs/frontend/tutorials/redux.md

dev/docs/frontend/tutorials/siteComponents.md

dev/docs/frontend/tutorials/usefulCss.md