Show minimal persistent example in Github project page and Hackage package page

[malteneuss]

Hi,
i would like to add the minimal usage example of the Yesod-Book in https://www.yesodweb.com/book/persistent#persistent_synopsis to the README so that it appears on the main Github project landing page and Hackage package landing page, because i really like this style from the Rust community; You can quickly copy-paste a working example and get a feel for the operators. See Serde, Rocket, Askama etc. Would that be desired?

Maybe make the example even shorter? E.g.

{-# LANGUAGE EmptyDataDecls             #-}
{-# LANGUAGE FlexibleContexts           #-}
{-# LANGUAGE GADTs                      #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MultiParamTypeClasses      #-}
{-# LANGUAGE OverloadedStrings          #-}
{-# LANGUAGE QuasiQuotes                #-}
{-# LANGUAGE TemplateHaskell            #-}
{-# LANGUAGE TypeFamilies               #-}
import           Control.Monad.IO.Class  (liftIO)
import           Database.Persist
import           Database.Persist.Sqlite
import           Database.Persist.TH
import           Data.Text

share [mkPersist sqlSettings, mkMigrate "migrateAll"] [persistLowerCase|
Person
    name Text
    age Int Maybe
    deriving Show
|]

main :: IO ()
main = runSqlite ":memory:" $ do
    -- setup db schema
    runMigration migrateAll
    
    -- write to db
    insert $ Person "Jane Doe" Nothing
    johnId <- insert $ Person "John Doe" $ Just 35

    -- read from db
    john1 <- selectList [PersonId ==. johnId] [LimitTo 1]
    john2 <- get johnId

    liftIO $ print (john1 :: [Entity Person])
    liftIO $ print (john2 :: Maybe Person)
    
    -- delete from db
    delete johnId
    deleteWhere [PersonId ==. johnId]

[malteneuss]

I added a PR. Ideally, the README with an example would also appear in Hackage: https://hackage.haskell.org/package/persistent. Please let me know how if that's desired as well and i could do that.

I would like to add similar minimal examples into the README of persistent-postgresql (and possible the others)