docs(readme): replace fastify.io links with fastify.dev (#115)

Signed-off-by: Frazer Smith <frazer.dev@outlook.com>

README.md

@@ -37,13 +37,13 @@ The Fastify's default [`ajv` options](https://github.com/ajv-validator/ajv/tree/
 Moreover, the [`ajv-formats`](https://www.npmjs.com/package/ajv-formats) module is included by default.
 If you need to customize it, check the _usage_ section below.
 
-To customize the `ajv`'s options, see how in the [Fastify official docs](https://www.fastify.io/docs/latest/Reference/Server/#ajv).
+To customize the `ajv`'s options, see how in the [Fastify official docs](https://www.fastify.dev/docs/latest/Reference/Server/#ajv).
 
 
 ## Usage
 
 This module is already used as default by Fastify. 
-If you need to provide to your server instance a different version, refer to [the official doc](https://www.fastify.io/docs/latest/Reference/Server/#schemacontroller).
+If you need to provide to your server instance a different version, refer to [the official doc](https://www.fastify.dev/docs/latest/Reference/Server/#schemacontroller).
 
 ### Customize the `ajv-formats` plugin
 
@@ -203,15 +203,15 @@ app.listen({ port: 3000 })
 
 ### How it works
 
-This module provide a factory function to produce [Validator Compilers](https://www.fastify.io/docs/latest/Reference/Server/#validatorcompiler) functions.
+This module provide a factory function to produce [Validator Compilers](https://www.fastify.dev/docs/latest/Reference/Server/#validatorcompiler) functions.
 
 The Fastify factory function is just one per server instance and it is called for every encapsulated context created by the application through the `fastify.register()` call.
 
 Every Validator Compiler produced, has a dedicated AJV instance, so, this factory will try to produce as less as possible AJV instances to reduce the memory footprint and the startup time.
 
 The variables involved to choose if a Validator Compiler can be reused are:
 
-- the AJV configuration: it is [one per server](https://www.fastify.io/docs/latest/Reference/Server/#ajv)
+- the AJV configuration: it is [one per server](https://www.fastify.dev/docs/latest/Reference/Server/#ajv)
 - the external JSON schemas: once a new schema is added to a fastify's context, calling `fastify.addSchema()`, it will cause a new AJV inizialization