Fix typo in proxy.md

Change-Id: Ic8481b3b139e2837683cf917929b7b89ac2c9fe4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2527792
Auto-Submit: David Benjamin <davidben@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Commit-Queue: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825534}

net/docs/proxy.md

@@ -469,7 +469,7 @@ implicitly](#Implicit-bypass-rules).
 
 *Subtracts* the [implicit proxy bypass rules](#Implicit-bypass-rules)
 (localhost and link local addresses). This is generally only needed for test
-setupe. Beware of the security implications to proxying localhost.
+setups. Beware of the security implications to proxying localhost.
 
 Whereas regular bypass rules instruct the browser about URLs that should *not*
 use the proxy, this rule has the opposite effect and tells the browser to