add mindspore.nn.probability

add mindspore.nn.probability

modify title underline

api/source_en/api/python/mindspore/mindspore.nn.probability.rst

+mindspore.nn.probability
+========================
+
+mindspore.nn.probability.distribution
+-------------------------------------
+
+.. automodule:: mindspore.probability.distribution
+    :members:
+
+mindspore.nn.probability.bijector
+---------------------------------
+
+.. automodule:: mindspore.probability.bijector
+    :members:

api/source_en/index.rst

@@ -19,6 +19,7 @@ MindSpore API
    api/python/mindspore/mindspore.nn
    api/python/mindspore/mindspore.nn.dynamic_lr
    api/python/mindspore/mindspore.nn.learning_rate_schedule
+   api/python/mindspore/mindspore.nn.probability
    api/python/mindspore/mindspore.ops
    api/python/mindspore/mindspore.ops.composite
    api/python/mindspore/mindspore.ops.operations

api/source_zh_cn/api/python/mindspore/mindspore.nn.probability.rst

+mindspore.nn.probability
+========================
+
+mindspore.nn.probability.distribution
+-------------------------------------
+
+.. automodule:: mindspore.nn.probability.distribution
+    :members:
+
+mindspore.nn.probability.bijector
+---------------------------------
+
+.. automodule:: mindspore.nn.probability.bijector
+    :members:

api/source_zh_cn/index.rst

@@ -19,6 +19,7 @@ MindSpore API
    api/python/mindspore/mindspore.nn
    api/python/mindspore/mindspore.nn.dynamic_lr
    api/python/mindspore/mindspore.nn.learning_rate_schedule
+   api/python/mindspore/mindspore.nn.probability
    api/python/mindspore/mindspore.ops
    api/python/mindspore/mindspore.ops.composite
    api/python/mindspore/mindspore.ops.operations