Add indication if C extension is installed

docs/source/get-started.rst

@@ -80,7 +80,7 @@ Check if the correct version is installed
     .. code-block:: console
 
         $ jsonyx --version
-        jsonyx 2.0.0
+        jsonyx 2.0.0 (C extension)
 
 .. tab:: short options
 
@@ -91,7 +91,10 @@ Check if the correct version is installed
     .. code-block:: console
 
         $ jsonyx -v
-        jsonyx 2.0.0
+        jsonyx 2.0.0 (C extension)
+
+.. note:: If the version number is followed by ``(Python)``, the C extension is
+    not installed.
 
 Quick start
 -----------

src/jsonyx/__init__.py

@@ -1,6 +1,5 @@
 # Copyright (C) 2024 Nice Zombies
 """Customizable JSON library for Python."""
-# TODO(Nice Zombies): test on Python 3.8
 # TODO(Nice Zombies): update badge branch
 from __future__ import annotations
 

src/jsonyx/__main__.py

@@ -7,7 +7,7 @@
 
 import sys
 from argparse import ArgumentParser
-from sys import stderr, stdin
+from sys import modules, stderr, stdin
 from traceback import format_exception_only
 from typing import Any, Literal, cast
 
@@ -46,9 +46,10 @@ class _PatchNameSpace(_Namespace):
 
 
 def _configure(parser: ArgumentParser) -> None:
-    parser.add_argument(
-        "-v", "--version", action="version", version=f"jsonyx {__version__}",
-    )
+    parser.add_argument("-v", "--version", action="version", version=(
+        f"jsonyx {__version__} "
+        f"({'C extension' if '_jsonyx' in modules else 'Python'})"
+    ))
     parent_parser: ArgumentParser = ArgumentParser(add_help=False)
     parent_parser.add_argument(
         "-a",