[docs] add documentation from the sources of the google engines

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

docs/src/searx.engines.google.rst

@@ -0,0 +1,55 @@
+.. _google engines:
+
+==============
+Google Engines
+==============
+
+.. contents:: Contents
+   :depth: 2
+   :local:
+   :backlinks: entry
+
+
+.. _google API:
+
+google API
+==========
+
+.. _Query Parameter Definitions:
+   https://developers.google.com/custom-search/docs/xml_results#WebSearch_Query_Parameter_Definitions
+
+For detailed description of the *REST-full* API see: `Query Parameter
+Definitions`_.  Not all parameters can be appied and some engines are *special*
+(e.g. :ref:`google news engine`).
+
+.. _google web engine:
+
+Google WEB
+==========
+
+.. automodule:: searx.engines.google
+  :members:
+
+.. _google images engine:
+
+Google Images
+=============
+
+.. automodule:: searx.engines.google_images
+  :members:
+
+.. _google videos engine:
+
+Google Videos
+=============
+
+.. automodule:: searx.engines.google_videos
+  :members:
+
+.. _google news engine:
+
+Google News
+===========
+
+.. automodule:: searx.engines.google_news
+  :members: