Update copy of pricing tiers, update readme instructions

[AvdLee]

• Updated the copy
• Added a Free plan instead of trial plan
• Change CTA of teams to start trial
• Changed pricing to monthly
• Removed all trialing dots to make things cleaner
• Introduced a price of €15 per month for enterprise, I feel like this is a great price to use and makes our pricing grow equally (€0, €5, €10, €15)
• All CTAs have the same primary color to indicate it's clickable UX. They're all equally "heavy/important", depending on the user
• Changed the color of the X SVG to be white, so the blue checkmark stands out more
• Updated the readme with instructions on changing directory before using npm (I always run into the same, haha)

[ngnijland]

Looking good!