[misc] Fix typo in middleware docs

docs/concepts/Middleware/Middleware.md

@@ -28,7 +28,7 @@ To configure a new custom HTTP middleware function, add a middleware function as
 With the exception of "order", which is reserved for configuring the order of the middleware stack, any value assigned to a key of `sails.config.middleware` should be a function which takes three arguments: `req`, `res` and `next`.  This function works almost exactly like a [policy](https://sailsjs.com/documentation/concepts/policies), the only visible difference is when it's executed.
 
 ##### Initializing middleware
-If you need to run some one-time set up code for a custom middleware function, you'll need to do so _before_ passing it in.  The recommended way of doing this is with a self-calling (i.e. ["immediately-invoked"](https://en.wikipedia.org/wiki/Immediately-invoked_function_expression)) wrapper function.  In the example below, note that rather than setting the value to a "req, res, next" function directly, a self-calling function is used to "wrap" some initial setup code.  That self-calling wrapper function then returns the final middleware (req,res,next) function, so it gets set on the key just the same was as if it had been passed in directly.
+If you need to run some one-time set up code for a custom middleware function, you'll need to do so _before_ passing it in.  The recommended way of doing this is with a self-calling (i.e. ["immediately-invoked"](https://en.wikipedia.org/wiki/Immediately-invoked_function_expression)) wrapper function.  In the example below, note that rather than setting the value to a "req, res, next" function directly, a self-calling function is used to "wrap" some initial setup code.  That self-calling wrapper function then returns the final middleware (req,res,next) function, so it gets set on the key just the same way as if it had been passed in directly.
 
 ##### Example: using custom middleware
 The following example shows how you might set up three different custom HTTP middleware functions: