docs: use sorted(glob()) in example setup.py (#2561)

docs/compiling.rst

@@ -31,13 +31,14 @@ An example of a ``setup.py`` using pybind11's helpers:
 
 
 .. code-block:: python
 .. code-block:: python
 
 
+    from glob import glob
     from setuptools import setup
     from setuptools import setup
     from pybind11.setup_helpers import Pybind11Extension
     from pybind11.setup_helpers import Pybind11Extension
 
 
     ext_modules = [
     ext_modules = [
         Pybind11Extension(
         Pybind11Extension(
             "python_example",
             "python_example",
-            ["src/main.cpp"],
+            sorted(glob("src/*.cpp")),  # Sort source files for reproducibility
         ),
         ),
     ]
     ]
 
 
@@ -52,13 +53,14 @@ that is supported via a ``build_ext`` command override; it will only affect
 
 
 .. code-block:: python
 .. code-block:: python
 
 
+    from glob import glob
     from setuptools import setup
     from setuptools import setup
     from pybind11.setup_helpers import Pybind11Extension, build_ext
     from pybind11.setup_helpers import Pybind11Extension, build_ext
 
 
     ext_modules = [
     ext_modules = [
         Pybind11Extension(
         Pybind11Extension(
             "python_example",
             "python_example",
-            ["src/main.cpp"],
+            sorted(glob("src/*.cpp")),
         ),
         ),
     ]
     ]
 
 
@@ -71,12 +73,14 @@ that is supported via a ``build_ext`` command override; it will only affect
 Since pybind11 does not require NumPy when building, a light-weight replacement
 Since pybind11 does not require NumPy when building, a light-weight replacement
 for NumPy's parallel compilation distutils tool is included. Use it like this:
 for NumPy's parallel compilation distutils tool is included. Use it like this:
 
 
+.. code-block:: python
+
     from pybind11.setup_helpers import ParallelCompile
     from pybind11.setup_helpers import ParallelCompile
 
 
     # Optional multithreaded build
     # Optional multithreaded build
     ParallelCompile("NPY_NUM_BUILD_JOBS").install()
     ParallelCompile("NPY_NUM_BUILD_JOBS").install()
 
 
-    setup(...
+    setup(...)
 
 
 The argument is the name of an environment variable to control the number of
 The argument is the name of an environment variable to control the number of
 threads, such as ``NPY_NUM_BUILD_JOBS`` (as used by NumPy), though you can set
 threads, such as ``NPY_NUM_BUILD_JOBS`` (as used by NumPy), though you can set