runhaskell doesn't work reliably for all users. Update quickstart in the README

[ocramz]

We should point users to stack or cabal.

See #389

[pbrinkmeier]

Hi, I investigated this a little. The readme currently contains this passage:

---

Run /basic.hs to see Scotty in action:

runghc examples/basic.hs

Setting phasers to stun... (port 3000) (ctrl-c to quit)

Or equivalently with stack:

stack exec -- scotty-basic

---

My results (using the haskell:9.6.4-slim Docker container):

• runghc doesn't work without installing dependencies globally
• stack exec -- scotty-basic doesn't work (anymore perhaps?)

What works:

• cabal update && cabal run scotty-basic
• stack run -- scotty-basic, but this requires a stack.yaml with the following content:

resolver:
  url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/22/15.yaml

packages:
- .
- examples

I.e. more maintenance work to keep this up to date. There might be another way to get stack to behave but I don't know it that well.

I'd suggest to just change it to cabal run scotty-basic with like a line or two saying that it will take a minute when running it the first time. I can prepare a PR for this :)

[ocramz]

@pbrinkmeier A PR would be very appreciated!