[2.1.x] Fixed #29440 -- Doc'd where the bulk argument applies in RelatedManager.

Backport of 74179296 from master

docs/ref/models/relations.txt

@@ -96,7 +96,7 @@ Related objects reference
         parameter ``blog`` to ``create()``. Django figures out that the new
         ``Entry`` object's ``blog`` field should be set to ``b``.
 
-    .. method:: remove(*objs)
+    .. method:: remove(*objs, bulk=True)
 
         Removes the specified model objects from the related object set::
 
@@ -129,7 +129,10 @@ Related objects reference
         :data:`~django.db.models.signals.post_save` signals and comes at the
         expense of performance.
 
-    .. method:: clear()
+        For many-to-many relationships, the ``bulk`` keyword argument doesn't
+        exist.
+
+    .. method:: clear(bulk=True)
 
         Removes all objects from the related object set::
 
@@ -143,6 +146,9 @@ Related objects reference
         :class:`~django.db.models.ForeignKey`\s where ``null=True`` and it also
         accepts the ``bulk`` keyword argument.
 
+        For many-to-many relationships, the ``bulk`` keyword argument doesn't
+        exist.
+
     .. method:: set(objs, bulk=True, clear=False)
 
         Replace the set of related objects::
@@ -156,7 +162,11 @@ Related objects reference
         If ``clear=True``, the ``clear()`` method is called instead and the
         whole set is added at once.
 
-        The ``bulk`` argument is passed on to :meth:`add`.
+        For :class:`~django.db.models.ForeignKey` objects, the ``bulk``
+        argument is passed on to :meth:`add` and :meth:`remove`.
+
+        For many-to-many relationships, the ``bulk`` keyword argument doesn't
+        exist.
 
         Note that since ``set()`` is a compound operation, it is subject to
         race conditions. For instance, new objects may be added to the database