PyPI: Link to Tutorial and Release Notes. Add Linux classifiers.

References #139

pyproject.toml

@@ -10,13 +10,15 @@ classifiers = [
     "Development Status :: 4 - Beta",
     "Environment :: MacOS X",
     "Environment :: Win32 (MS Windows)",
+    "Environment :: X11 Applications",
     "Intended Audience :: End Users/Desktop",
     "Intended Audience :: Information Technology",
     "Intended Audience :: System Administrators",
     "License :: Other/Proprietary License",
     "Natural Language :: English",
     "Operating System :: MacOS :: MacOS X",
     "Operating System :: Microsoft :: Windows",
+    "Operating System :: POSIX :: Linux",
     "Topic :: Internet :: WWW/HTTP",
     "Topic :: Internet :: WWW/HTTP :: Browsers",
     "Topic :: Internet :: WWW/HTTP :: Indexing/Search",
@@ -33,6 +35,10 @@ include = [
     "README/[email protected]",
 ]
 
+[tool.poetry.urls]
+"Tutorial" = "https://github.com/davidfstr/Crystal-Web-Archiver/tree/main#tutorial-"
+"Release notes" = "https://github.com/davidfstr/Crystal-Web-Archiver/blob/main/RELEASE_NOTES.md"
+
 [tool.poetry.scripts]
 # Install "crystal" binary as CLI command. Allow installation via "pipx".
 crystal = 'crystal.__main__:main'