docs: remove repeated section from performance guide (#1824)

Signed-off-by: Dustin Popp <[email protected]>

Author: Dustin Popp

en/advanced/best-practice-performance.md

@@ -143,7 +143,7 @@ Additionally, using `uncaughtException` is officially recognized as [crude](http
 
 We also don't recommend using [domains](https://nodejs.org/api/domain.html). It generally doesn't solve the problem and is a deprecated module.
 
-## Things to do in your environment / setup 
+## Things to do in your environment / setup
 {#in-environment}
 
 Here are some things you can do in your system environment to improve your app's performance:
@@ -309,5 +309,3 @@ With load balancing, you might have to ensure that requests that are associated
 A reverse proxy sits in front of a web app and performs supporting operations on the requests, apart from directing requests to the app. It can handle error pages, compression, caching, serving files, and load balancing among other things.
 
 Handing over tasks that do not require knowledge of application state to a reverse proxy frees up Express to perform specialized application tasks. For this reason, it is recommended to run Express behind a reverse proxy like [Nginx](https://www.nginx.org/) or [HAProxy](https://www.haproxy.org/) in production.
-
-Handing over tasks that do not require knowledge of application state to a reverse proxy frees up Express to perform specialized application tasks. For this reason, it is recommended to run Express behind a reverse proxy like [Nginx](https://www.nginx.com/) or [HAProxy](http://www.haproxy.org/) in production.