Fix Tree and TreeSequence docstrings

Author: benjeffery

python/tskit/trees.py

@@ -575,8 +575,8 @@ class Migration(util.Dataclass):
     """
     id: int  # noqa A003
     """
-    The integer ID of this mutation. Varies from 0 to
-    :attr:`TreeSequence.num_mutations` - 1.
+    The integer ID of this migration. Varies from 0 to
+    :attr:`TreeSequence.num_migrations` - 1.
     """
 
 
@@ -774,7 +774,7 @@ def root_threshold(self):
         calling the :meth:`TreeSequence.trees` iterator.
 
         :return: The root threshold.
-        :rtype: :class:`TreeSequence`
+        :rtype: int
         """
         return self._ll_tree.get_root_threshold()
 
@@ -885,7 +885,8 @@ def seek(self, position, skip=None):
 
         :param float position: The position along the sequence length to
             seek to.
-        :raises ValueError: If 0 < position or position >=
+        :raises ValueError: If ``position`` is less than 0 or ``position`` is greater
+            than or equal to
             :attr:`TreeSequence.sequence_length`.
         """
         if position < 0 or position >= self.tree_sequence.sequence_length:
@@ -922,7 +923,7 @@ def unrank(num_leaves, rank, *, span=1, branch_length=1) -> Tree:
             the interval :math:`[0, \\text{span})` and the :attr:`~Tree.tree_sequence`
             from which the tree is taken will have its
             :attr:`~tskit.TreeSequence.sequence_length` equal to ``span``.
-        :param: float branch_length: The minimum length of a branch in this tree.
+        :param float branch_length: The minimum length of a branch in this tree.
         :raises ValueError: If the given rank is out of bounds for trees
             with ``num_leaves`` leaves.
         """
@@ -11004,12 +11005,12 @@ def map_to_vcf_model(
         return an integer numpy array the same dimension as the input. By default,
         this is set to ``numpy.round()`` which will round values to the nearest integer.
 
-        If neither `name_metadata_key` nor `individual_names` is not specified, the
-        individual names are set to "tsk_{individual_id}" for each individual. If
+        If neither `name_metadata_key` nor `individual_names` is specified, the
+        individual names are set to ``"tsk_{individual_id}"`` for each individual. If
         no individuals are present, the individual names are set to "tsk_{i}" with
         `0 <= i < num_sample_nodes/ploidy`.
 
-        A Warning are emmitted if any sample nodes do not have an individual ID.
+        A warning is emitted if any sample nodes do not have an individual ID.
 
         :param list individuals: Specific individual IDs to include in the VCF. If not
             specified and the tree sequence contains individuals, all individuals are