Rename c++11.md

Given that the file is about more than just C++11, it should have a
name reflecting that fact. Rename it to c++-features.md as it's about
the new features of the C++ language and whether they're allowed for
use.

Bug: none
Change-Id: If97a7e27ea69280f1e220a6e021e9b62a5af074d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3399246
Auto-Submit: Avi Drissman <avi@chromium.org>
Reviewed-by: danakj chromium <danakj@chromium.org>
Reviewed-by: Charles Reis <creis@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#960626}
NOKEYCHECK=True
GitOrigin-RevId: 0aafa9e4fd4c6e8d2a7f762b7b1cdf25bd553313

README.chromium

diff --git a/README.chromium b/README.chromium
index 0106205..f8eb8ce 100644
--- a/README.chromium
+++ b/README.chromium
@@ -10,7 +10,7 @@
 Description:
 This directory contains the source code of Abseil for C++. This can be used by
 Chromium, subject to the guidance at
-https://chromium.googlesource.com/chromium/src/+/main/styleguide/c++/c++11.md;
+https://chromium.googlesource.com/chromium/src/+/main/styleguide/c++/c++-features.md;
 it can be used without restriction by Chromium's dependencies, except that
 objects compiled into Chromium itself cannot use anything relying on
 absl::base_internal::FastTypeId (see https://crbug.com/1096380).