gh-100150: document that --without-doc-strings affects inspect.signature

Add a note to the --without-doc-strings documentation explaining that
disabling docstrings also prevents inspect.signature() from retrieving
signatures for built-in functions and methods implemented in C, since
those signatures are embedded in their docstrings by Argument Clinic.

Author: Gh-Novel

Doc/using/configure.rst

@@ -813,6 +813,17 @@ also be used to improve performance.
 
    See the ``PyDoc_STRVAR()`` macro.
 
+   .. note::
+
+      Disabling doc strings also means that :func:`inspect.signature` cannot
+      retrieve signatures for built-in functions and methods implemented in C,
+      since the signatures for these functions are embedded in their docstrings
+      (generated by `Argument Clinic
+      <https://devguide.python.org/development-tools/clinic/>`_). This may
+      affect tools and libraries that rely on introspecting built-in callables,
+      such as :func:`help` and some third-party frameworks.
+
+
 .. option:: --enable-profiling
 
    Enable C-level code profiling with ``gprof`` (disabled by default).