add api.rst

docs/source/api.rst

+..
+   DO NOT DELETE THIS FILE! It contains the all-important `.. autosummary::` directive with `:recursive:` option, without
+   which API documentation wouldn't get extracted from docstrings by the `sphinx.ext.autosummary` engine. It is hidden
+   (not declared in any toctree) to remove an unnecessary intermediate page; index.rst instead points directly to the
+   package page. DO NOT REMOVE THIS FILE!.. autosummary::
+
+:toctree: _autosummary
+:template: custom-module-template.rst
+:recursive:
+
+aliby
+extraction