[3.11] gh-113560: Improve docstrings for set.issubset() and set.issuperset() (GH-113562) (GH-114643)

(cherry picked from commit 11c5822)

Co-authored-by: Charlie Zhao <zhaoyu_hit@qq.com>

Author: miss-islington

Objects/setobject.c

@@ -1761,7 +1761,11 @@ set_issubset(PySetObject *so, PyObject *other)
     Py_RETURN_TRUE;
 }
 
-PyDoc_STRVAR(issubset_doc, "Report whether another set contains this set.");
+PyDoc_STRVAR(issubset_doc,
+"issubset($self, other, /)\n\
+--\n\
+\n\
+Test whether every element in the set is in other.");
 
 static PyObject *
 set_issuperset(PySetObject *so, PyObject *other)
@@ -1793,7 +1797,11 @@ set_issuperset(PySetObject *so, PyObject *other)
     Py_RETURN_TRUE;
 }
 
-PyDoc_STRVAR(issuperset_doc, "Report whether this set contains another set.");
+PyDoc_STRVAR(issuperset_doc,
+"issuperset($self, other, /)\n\
+--\n\
+\n\
+Test whether every element in other is in the set.");
 
 static PyObject *
 set_richcompare(PySetObject *v, PyObject *w, int op)