Use short markdown description file for pypi page

Author: andsens

docs/README.pypi.md

@@ -0,0 +1,7 @@
+docopt.sh
+=========
+
+A [docopt](http://docopt.org/) argument parser for bash 3.2, 4+, and 5+ with no
+external dependencies.
+
+The full documentation is available on [GitHub](https://github.com/andsens/docopt.sh#docoptsh).

pyproject.toml

@@ -8,7 +8,7 @@ module = "docopt_sh"
 author = "Anders Ingemann"
 author-email = "[email protected]"
 home-page = "https://github.com/andsens/docopt.sh"
-description-file = "README.adoc"
+description-file = "docs/README.pypi.md"
 classifiers = [
   "Topic :: Utilities",
   "Programming Language :: Python :: 3",