README: make new section for asset management

{{cookiecutter.app_name}}/README.rst

@@ -40,23 +40,6 @@ database tables and perform the initial migration ::
     flask db upgrade
     flask run
 
-Files placed inside the ``assets`` directory and its subdirectories
-will be copied by webpack's ``file-loader`` into the ``static/build``
-directory, with hashes of their contents appended to their names.  For
-instance, if you have the file ``assets/img/favicon.ico``, this will
-get copied into something like
-``static/build/img/favicon.fec40b1d14528bf9179da3b6b78079ad.ico``.
-You can then put this line into your header::
-
-    <link rel="shortcut icon" href="{{ "{{" }}asset_url_for('img/favicon.ico') {{ "}}" }}">
-
-to refer to it inside your HTML page.  If all of your assets are
-managed this way, you can ask Flask to tell web browsers that they
-should cache your static files forever by including the following line
-in your ``settings.py``::
-
-    SEND_FILE_MAX_AGE_DEFAULT = 31556926  # one year
-
 
 Deployment
 ----------
@@ -103,3 +86,26 @@ This will generate a new migration script. Then run ::
 To apply the migration.
 
 For a full migration command reference, run ``flask db --help``.
+
+
+Asset Management
+----------------
+
+Files placed inside the ``assets`` directory and its subdirectories
+(excluding ``js`` and ``css``) will be copied by webpack's
+``file-loader`` into the ``static/build`` directory, with hashes of
+their contents appended to their names.  For instance, if you have the
+file ``assets/img/favicon.ico``, this will get copied into something
+like
+``static/build/img/favicon.fec40b1d14528bf9179da3b6b78079ad.ico``.
+You can then put this line into your header::
+
+    <link rel="shortcut icon" href="{{ "{{" }}asset_url_for('img/favicon.ico') {{ "}}" }}">
+
+to refer to it inside your HTML page.  If all of your static files are
+managed this way, then their filenames will change whenever their
+contents do, and you can ask Flask to tell web browsers that they
+should cache all your assets forever by including the following line
+in your ``settings.py``::
+
+    SEND_FILE_MAX_AGE_DEFAULT = 31556926  # one year