Fix/improve pyproject.toml metadata #160

* Incorrect README path causing issues with publishing
    * Introduced in #151.
* Point to `LICENSE` file
* Add myself to authors list

MANIFEST.in

@@ -1,3 +1,3 @@
 include AUTHORS
-include README.md
+include README.rst
 include LICENSE

pyproject.toml

@@ -6,10 +6,13 @@ build-backend = "setuptools.build_meta"
 name = "pynrrd"
 dynamic = ["version"]
 description = "Pure python module for reading and writing NRRD files."
-readme = { file = "README.txt", content-type = "text/x-rst" }
+readme = { file = "README.rst", content-type = "text/x-rst" }
 requires-python = ">=3.7"
-license = { text = "MIT License" }
-authors = [{ name = "Maarten Everts", email = "me@nn8.nl" }]
+license = { file = "LICENSE" }
+authors = [
+    { name = "Maarten Everts", email = "me@nn8.nl" },
+    { name = "Addison Elliott", email = "addison.elliott@gmail.com" }
+]
 keywords = ["nrrd", "teem", "image", "processing", "file", "format"]
 classifiers = [
     "License :: OSI Approved :: MIT License",