DevTools: remove network overrides from what's new

The network overrides feature was reverted from enabled by default here:
https://chromium-review.googlesource.com/c/chromium/src/+/801574

TBR=pfeldman@chromium.org

Bug: 789652
Change-Id: Id90e76fae69712c644f8b8ea177636f638461249
Reviewed-on: https://chromium-review.googlesource.com/802321
Commit-Queue: Will Chen <chenwilliam@chromium.org>
Reviewed-by: Will Chen <chenwilliam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520854}

third_party/WebKit/Source/devtools/front_end/help/ReleaseNoteText.js

@@ -15,11 +15,6 @@ Help.releaseNoteText = [
     version: 7,
     header: 'Highlights from the Chrome 64 update',
     highlights: [
-      {
-        title: 'Local overrides',
-        subtitle: 'Persist your HTML, CSS, and JS changes across page loads.',
-        link: 'https://developers.google.com/web/updates/2017/11/devtools-release-notes#overrides',
-      },
       {
         title: 'Performance monitor',
         subtitle: 'Get a real-time view of various performance metrics.',