Add license, license_files, long_description_content_type, long_descr…

…iption in pyktx setup.py (#844)

@MarkCallow
#698 (comment)

interface/python_binding/setup.py

@@ -21,8 +21,12 @@
     ],
     include_package_data=True,
     install_requires=["cffi>=1.15.1"],
+    license="Apache 2.0",
+    license_files=('LICENSE'),
+    long_description_content_type="text/markdown",
+    long_description="This Python package provides a Pythonic interface to libktx. It uses CFFI to generate the C bindings.",
     packages=['pyktx'],
     package_dir={'pyktx': 'pyktx'},
     setup_requires=["cffi>=1.15.1"],
-    url='https://github.com/KhronosGroup/KTX-Software'
+    url='https://github.com/KhronosGroup/KTX-Software',
 )