[3.15] Fix typo in C API Introduction documentation (GH-160563) (#160581)

(cherry picked from commit 94942ba)

Co-authored-by: Michael Newman <michael.b.newman@gmail.com>

Author: miss-islington

Doc/c-api/intro.rst

@@ -935,7 +935,7 @@ use them.
              PY_SSIZE_T_MIN
 
    The limit values (largest positive one and smallest negative one,
-   respecitvely) of type :c:type:`Py_ssize_t`.
+   respectively) of type :c:type:`Py_ssize_t`.
 
 
 .. c:macro:: PY_DWORD_MAX