[PFX-1136]: add doc for removing @fastify/express package (#1360)

* add doc for removing fastify/express

* remove section referencing fastify/express

* reference gasket actions in documentation for replacing res.locals

* changeset

* move guide to fastify plugin

* add link to guide in fastify readme

* regen changeset

Author: bbetts-godaddy

.changeset/sharp-fans-call.md

@@ -0,0 +1,5 @@
+---
+"@gasket/plugin-fastify": patch
+---
+
+Create guide for removing @fastify/express package

packages/gasket-plugin-fastify/README.md

@@ -115,6 +115,10 @@ export default {
 
 This plugins hooks the [createServers] lifecycles from [@gasket/plugin-https].
 
+## Guides
+
+- [Removing @fastify/express] - Migration guide for removing `@fastify/express` dependency and using native Fastify patterns
+
 ## License
 
 [MIT](./LICENSE.md)
@@ -123,3 +127,4 @@ This plugins hooks the [createServers] lifecycles from [@gasket/plugin-https].
 
 [@gasket/plugin-https]:/packages/gasket-plugin-https/README.md
 [createServers]:/packages/gasket-plugin-https/README.md#createservers
+[Removing @fastify/express]:docs/remove-fastify-express.md