message: Update style guide about C++17
  Cr-Commit-Position: refs/heads/main@{#35589}
diff: @@ -25,12 +25,12 @@ both.
  ### C++ version
  -WebRTC is written in C++14, but with some restrictions:
  +WebRTC is written in C++17, but with some restrictions:
  -* We only allow the subset of C++14 (language and library) that is not banned by
  +* We only allow the subset of C++17 (language and library) that is not banned by
  Chromium; see the [list of banned C++ features in Chromium][chr-style-cpp].
  -* We only allow the subset of C++14 that is also valid C++17; otherwise, users
  - would not be able to compile WebRTC in C++17 mode.
  +* We only allow the subset of C++17 that is also valid C++20; otherwise, users
  + would not be able to compile WebRTC in C++20 mode.
  [chr-style-cpp]: https://chromium.googlesource.com/chromium/src/+/main/styleguide/c++/c++11.md
  