Standardize component structure, update LinkWithDescription and LinkCard

[pstackebrandt]

• update structure of LinkWithDescription (currently single file)
• Add README to LinkCard folder

Partialy used structure for components:
src/components/
ComponentName/
index.js // Main component file
ComponentName.js // Alternative to index.js if preferred
ComponentName.scss
README.md
config.js // If needed
tests/ // For component tests