Merge pull request #209 from tomascassidy/patch-1

Fix typo in README.md

Author: oreoshake

README.md

@@ -15,7 +15,7 @@ The gem will automatically apply several headers that are related to security.
 - X-Permitted-Cross-Domain-Policies - [Restrict Adobe Flash Player's access to data](https://www.adobe.com/devnet/adobe-media-server/articles/cross-domain-xml-for-streaming.html)
 - Public Key Pinning - Pin certificate fingerprints in the browser to prevent man-in-the-middle attacks due to compromised Certificate Authorities. [Public Key Pinning Specification](https://tools.ietf.org/html/rfc7469)
 
-`secure_headers` is a library with a global config, per request overrides, and rack milddleware that enables you customize your application settings.
+`secure_headers` is a library with a global config, per request overrides, and rack middleware that enables you customize your application settings.
 
 ## Use