bpo-27351: Fix ConfigParser.read() documentation and docstring (GH-8123)

Switch "list" with "iterable" to match with the implementation.
diff --git a/Doc/library/configparser.rst b/Doc/library/configparser.rst
index 1e5f25f..0ae466e 100644
--- a/Doc/library/configparser.rst
+++ b/Doc/library/configparser.rst
@@ -963,16 +963,17 @@
 
    .. method:: read(filenames, encoding=None)
 
-      Attempt to read and parse a list of filenames, returning a list of
+      Attempt to read and parse an iterable of filenames, returning a list of
       filenames which were successfully parsed.
 
       If *filenames* is a string, a :class:`bytes` object or a
       :term:`path-like object`, it is treated as
       a single filename.  If a file named in *filenames* cannot be opened, that
-      file will be ignored.  This is designed so that you can specify a list of
-      potential configuration file locations (for example, the current
-      directory, the user's home directory, and some system-wide directory),
-      and all existing configuration files in the list will be read.
+      file will be ignored.  This is designed so that you can specify an
+      iterable of potential configuration file locations (for example, the
+      current directory, the user's home directory, and some system-wide
+      directory), and all existing configuration files in the iterable will be
+      read.
 
       If none of the named files exist, the :class:`ConfigParser`
       instance will contain an empty dataset.  An application which requires