Extensions Docserver: Bump the version.

This CL bumps the Docserver version to 3.58.0. r578728 introduced the
onActionIgnored event to the web request API. However, the documentation changes
are not yet reflected in the extension docs (due to an underlying Docserver
bug). Force a version bump for now, which should help reflect the new changes.

BUG=513780, 111700

Change-Id: I5ef403922b4e5d0c4af0d136b9ea0b8fecf528bc
Reviewed-on: https://chromium-review.googlesource.com/1182420Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Commit-Queue: Karan Bhatia <karandeepb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584612}

chrome/common/extensions/docs/server2/app.yaml

 application: chrome-apps-doc
-version: 3-57-0
+version: 3-58-0
 runtime: python27
 api_version: 1
 threadsafe: false