[Docs] Improve contribution docs (#15872)

Adds notes discussed in #14354 and #15592 , specifically
about AUTHORS being optional, and linking to the code style docs.

Author: mmarczell-graphisoft

AUTHORS

@@ -586,3 +586,4 @@ a license to everyone to use it as detailed in LICENSE.)
 * Nathan Rugg <[email protected]> (copyright owned by Chess.com, LLC)
 * Alexander O'Mara <[email protected]>
 * Kamaron Peterson <[email protected]>
+* Márton Marczell <[email protected]> (copyright owned by GRAPHISOFT SE)

site/source/docs/contributing/AUTHORS.rst

@@ -5,8 +5,7 @@ AUTHORS
 =======
 
 The `AUTHORS <https://github.com/emscripten-core/emscripten/blob/main/AUTHORS>`_ file lists everyone who has contributed to Emscripten.
-
-.. note :: Authors must add themselves to the `AUTHORS <https://github.com/emscripten-core/emscripten/blob/main/AUTHORS>`_ file before :doc:`contributing <contributing>`. This act licenses their changes under the project’s :ref:`open source licenses (MIT/LLVM) <emscripten-license>`. Note that the developer retains copyright.
+It is optional for a contributor to add themselves to the `AUTHORS <https://github.com/emscripten-core/emscripten/blob/main/AUTHORS>`_ file before :doc:`contributing <contributing>`.
 
 The contributors for releases up to Emscripten |release| inclusive (|today|) are listed below.
 

site/source/docs/contributing/developers_guide.rst

@@ -30,7 +30,7 @@ binaries with a checkout of the core Emscripten repository, simply by calling
 ``emcc.py`` from that checkout, and it will use the binaries from the emsdk.
 
 If you do want to contribute to LLVM or Binaryen, or to test modifications
-to them, you can 
+to them, you can
 :ref:`build them from source <installing-from-source>`.
 
 Repositories and branches of interest
@@ -55,6 +55,8 @@ When submitting patches, please:
   in ``tests/*.py`` for related tests, as often the simplest thing is to add to
   an existing one. If you're not sure how to test your code, feel free to ask
   for help.
+- Pay attention to our coding style specified in
+  `.clang-format <https://github.com/emscripten-core/emscripten/blob/main/.clang-format>`_.
 - We normally squash and merge PRs, which means the PR turns into a single
   commit on the target branch. Because of that, it's ok to have merge commits
   in the PR itself, as they get removed. Please put a good description for