Docs: Improve getting started section

[marvinhagemeister]

The "getting started" section in our docs is way too wordy and could be simplified. I want to avoid a first impression that you'd need to read half a book to get started with Fresh.

These are best to be worked on in separate PRs to make it easier to review.

A couple of thoughts looking at the getting started pages:

• The "Introduction" page should be merged with the "Getting Started" overview page. The text in the introduction page uses too many buzzwords and needs to many paragraphs to explain what Fresh is about
• The content on the "Getting Started" page feels like filler content
• Description of files on "Create a project" page is too long. Should be a short bullet point list
  • I like the file + folder explanation though, maybe we can make it even better
• The "Running locally" page should be merged with "Create a project". Feels odd to have a whole page describing how to execute one command
  • Commands should use -A there instead of listing each flag individually. We should have an accompanying info box that explains the permissions Fresh need. That makes it clear that this is secondary information. We use -A in the project that's bootstrapped via the init script too
• The "Create a route" page is too much text for explaining what a route is
• The "Dynamic routes" page should be merged into "Create a route" and simplified as well
• The "Fetching data" page should be before "custom handlers", The content in "Fetching data" should come first as it's the immediate onboarding path to get something visible on the screen for users
• The "Custom handlers" page should be merged into "Form submissions". Instead of going the URL route, the "Form submission" example should do a proper submit
• The "Deploy to production" page should not just be text. It should show how to deploy Fresh.

In general the getting started guide should be aimed at getting new users up and running and have a deployed site as quickly as possible.