docs(readme): create options, add more headings

[julie-ng]

As a developer, I want complete samples incl. minimum client configuration options, which would include the redis client password.

I had to manually open the ioredis documentation to check if it expected a password or secret configuration option. Probably the former. But including an example here saves first time users the trouble of looking it up - thanks 🙂 🙏

Original

In the original, only the hostname was provided.

fastify.register(require('fastify-redis'), { host: '127.0.0.1' })
// or
fastify.register(require('fastify-redis'), { url: 'redis://127.0.0.1', /* other redis options */ })

Btw - why was it host in the first example and then url?

Suggestion

Changes the 2nd example to include some common options, esp. password

fastify.register(require('fastify-redis'), { 
  host: '127.0.0.1', 
  password: '***',
  port: 6379, // Redis port
  family: 4   // 4 (IPv4) or 6 (IPv6)
})

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[darkgl0w]

Thank you for your PR :)

A little nit.
LGTM with the suggested change. ^^

[mcollina]

lgtm

[darkgl0w]

LGTM with @Fdawgs suggested changes. ^^

[julie-ng]

@Fdawgs okay your changes have been applied :)