!375 dataset: adjust config in api document into a single page

Merge pull request !375 from ms_yan/config_modify

api/source_en/api/python/mindspore/mindspore.dataset.config.rst

+mindspore.dataset.config
+=================
+
+.. automodule:: mindspore.dataset.config
+    :members:

api/source_en/api/python/mindspore/mindspore.dataset.rst

@@ -5,7 +5,3 @@ mindspore.dataset
     :members:
     :inherited-members:
     :exclude-members: get_args, read_dir
-
-.. autoclass:: mindspore.dataset.core.configuration.ConfigurationManager
-    :members:
-.. autodata:: config

api/source_en/index.rst

@@ -23,6 +23,7 @@ MindSpore API
    api/python/mindspore/mindspore.parallel
    api/python/mindspore/mindspore.train
    api/python/mindspore/mindspore.dataset
+   api/python/mindspore/mindspore.dataset.config
    api/python/mindspore/mindspore.dataset.text.transforms
    api/python/mindspore/mindspore.dataset.text.utils
    api/python/mindspore/mindspore.dataset.transforms.c_transforms

api/source_zh_cn/api/python/mindspore/mindspore.dataset.config.rst

+mindspore.dataset.config
+=================
+
+.. automodule:: mindspore.dataset.config
+    :members:

api/source_zh_cn/api/python/mindspore/mindspore.dataset.rst

@@ -5,7 +5,3 @@ mindspore.dataset
     :members:
     :inherited-members:
     :exclude-members: get_args, read_dir
-
-.. autoclass:: mindspore.dataset.core.configuration.ConfigurationManager
-    :members:
-.. autodata:: config

api/source_zh_cn/index.rst

@@ -23,6 +23,7 @@ MindSpore API
    api/python/mindspore/mindspore.parallel
    api/python/mindspore/mindspore.train
    api/python/mindspore/mindspore.dataset
+   api/python/mindspore/mindspore.dataset.config
    api/python/mindspore/mindspore.dataset.text.transforms
    api/python/mindspore/mindspore.dataset.text.utils
    api/python/mindspore/mindspore.dataset.transforms.c_transforms