add documentation for treevalue.config

docs/source/api_doc/config/index.rst

+treevalue.config
+=====================
+
+.. toctree::
+    :maxdepth: 3
+
+    meta

docs/source/api_doc/config/meta.rst

+treevalue.config.meta
+==========================
+
+.. automodule:: treevalue.config.meta
+
+

docs/source/api_doc/index.rst

@@ -4,4 +4,5 @@ Api Documentation
 .. toctree::
     :maxdepth: 3
 
+    config/index
     utils/index

treevalue/config/meta.py

+"""
+Overview:
+    Meta information for treevalue package.
+
+.. data:: __TITLE__
+
+    Title of this project (should be `treevalue`).
+
+.. data:: __VERSION__
+
+    Version of this project.
+
+.. data:: __AUTHOR__
+
+    Author of this project.
+
+.. data:: __AUTHOR_EMAIL__
+
+    Email of the author.
+"""
+
 __TITLE__ = "treevalue"
 __VERSION__ = "0.0.1b0"
 __AUTHOR__ = "HansBug"