Add Load Impact to README

Author: tomchristie

README.md

@@ -193,7 +193,7 @@ Send a description of the issue via email to [rest-framework-security@googlegrou
 [stream-img]: https://raw.githubusercontent.com/encode/django-rest-framework/master/docs/img/premium/stream-readme.png
 [rollbar-img]: https://raw.githubusercontent.com/encode/django-rest-framework/master/docs/img/premium/rollbar-readme.png
 [cadre-img]: https://raw.githubusercontent.com/encode/django-rest-framework/master/docs/img/premium/cadre-readme.png
-[load-impact-img]: https://raw.githubusercontent.com/encode/django-rest-framework/master/docs/img/premium/load-imapct-readme.png
+[load-impact-img]: https://raw.githubusercontent.com/encode/django-rest-framework/master/docs/img/premium/load-impact-readme.png
 
 [rover-url]: http://jobs.rover.com/
 [sentry-url]: https://getsentry.com/welcome/