docs(readme): update plugin version syntax (#254)

Author: Fdawgs

README.md

@@ -15,9 +15,9 @@ npm i @fastify/auth
 ### Compatibility
 | Plugin version | Fastify version |
 | ---------------|-----------------|
-| `^5.x`         | `^5.x`          |
-| `^3.x`         | `^4.x`          |
-| `^1.x`         | `^3.x`          |
+| `>=5.x`        | `^5.x`          |
+| `>=3.x <5.x`   | `^4.x`          |
+| `>=1.x <3.x`   | `^3.x`          |
 | `^0.x`         | `^2.x`          |
 | `^0.x`         | `^1.x`          |