Add brief overview docstring for converter module

[skip ci]

Author: rlskoeser

docs/undate/converters.rst

@@ -5,8 +5,9 @@ Overview
 --------
 
 
-..note: base converter is pretty developer-facing documentation; 
-.. calendar/converter usage would be helpful to add
+.. automodule:: undate.converters
+
+-----
 
 .. automodule:: undate.converters.base
    :members:
@@ -42,6 +43,8 @@ Extended Date-Time Format (EDTF)
 Calendars
 ---------
 
+.. automodule:: undate.converters.calendars
+
 Gregorian
 ^^^^^^^^^
 

src/undate/converters/__init__.py

@@ -1,3 +1,29 @@
+"""
+Converter classes add support for parsing and serializing dates
+in a variety of formats. A subset of these are calendar converters
+(:mod:`undate.converters.calendar`), which means they support both parsing
+and conversion from an alternate calendar to a common Gregorian
+for comparison across dates.
+
+To parse a date with a supported converter, use the ``Undate`` class method
+:meth:`~undate.undate.Undate.parse` and specify the date as a string
+with the desired format or calendar, e.g.
+
+.. code-block::
+
+  Undate.parse("2001-05", "EDTF")
+  Undate.parse("7 Heshvan 5425", "Hebrew")
+
+For converters that support it, you can also serialize a date in a specified
+format with ``Undate`` class method :meth:`~undate.undate.Undate.format`:
+
+.. code-block::
+
+  Undate.parse("Rabīʿ ath-Thānī 343", "Islamic").format("EDTF")
+
+
+"""
+
 from undate.converters.base import BaseDateConverter, GRAMMAR_FILE_PATH
 
 __all__ = ["BaseDateConverter", "GRAMMAR_FILE_PATH"]