Update 04_goingfunctional.md

fix typo

Author: hipertracker

packages/overmind-website/guides/intermediate/04_goingfunctional.md

@@ -48,12 +48,12 @@ To compose the different operators together you typically use **pipe**. You can
 h(Example, { name: "guide/goingfunctional/pipe" })
 ```
 
-There are several operators available and you can quite easily create new operators from scratch. They er built with the [op-op spec](https://github.com/christianalfoni/op-op-spec). A specification designed specifically to move state management solutions into a functional world.
+There are several operators available and you can quite easily create new operators from scratch. They are built with the [op-op spec](https://github.com/christianalfoni/op-op-spec). A specification designed specifically to move state management solutions into a functional world.
 
 ## Factories
 
 A familiar concept in functional programming is the use of factories. A factory is a function that creates an operator. This can be used to send *options* to an operator. A typical example of this is the **lengthGreaterThan** operator we built previously.
 
 ```marksy
 h(Example, { name: "guide/goingfunctional/factory" })
-```
+```