Extract developer instructions to a separate file

README.md is intended for end users so I think it’s good to move
information they don’t need elsewhere.

DEVELOPMENT.md

@@ -0,0 +1,28 @@
+Development
+===========
+
+To install in development mode with all required development and testing
+dependencies:
+
+    # pip3 install -e .[dev]
+
+To run the tests:
+
+    # ./test
+
+
+Packaging
+---------
+
+To build the wheel, first install in development mode with `[dev]` extras. This
+will ensure that pep517 and twine are installed.
+
+Build the wheel with pep517's build command:
+
+    # python3 -m pep517.build .
+
+Upload new the version to PyPI:
+
+    # python3 -m twine upload dist/*
+
+

README.md

@@ -105,34 +105,6 @@ should look something like this:
     crw-rw-rw- 1 root   root   1, 9 Jun 10 16:19 urandom
 
 
-Development
------------
-
-To install in development mode with all required development and testing
-dependencies:
-
-    # pip3 install -e .[dev]
-
-To run the tests:
-
-    # ./test
-
-
-Packaging
----------
-
-To build the wheel, first install in development mode with `[dev]` extras. This
-will ensure that pep517 and twine are installed.
-
-Build the wheel with pep517's build command:
-
-    # python3 -m pep517.build .
-
-Upload new the version to PyPI:
-
-    # python3 -m twine upload dist/*
-
-
 License
 -------