Add syntax highlighting to code example

[coderaiser]

So it looks this way:

import sqlLint from 'sql-lint'

// using async/await

const errors = await sqlLint({
  sql: 'SELECT my_column FROM my_table',
})

// or using promise

sqlLint({ sql: 'SELECT my_column FROM my_table' }).then(errors => {
  for (const error of errors) {
    // do something
  }
})