update READme

[lisahns]

Day 1: what we did:

• create memory container
• we insert and randomise dummy data
• when two li elements are clicked, they are compared: if match -> hide card + add points
• show points dynamically to the page
• get level and start the game based on the level

what we struggled with:

• re-randomising on every render when using useState()
• extracting randomiser from game component
• implementing css grid

what we learned:

• using className instead of class inside html attributes in react
• better sense of how useState() and useEffect() work -> whole component will re-render
• importance of modularisation in react

What to do tomorrow:

• when all cards are matched go to next level
• when level 5 is completed show win screen
• css
• useState() for guesses and score