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

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

searx/engines/google_images.py

@@ -1,19 +1,14 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 # lint: pylint
-"""Google (Images)
+"""This is the implementation of the google images engine.
 
-For detailed description of the *REST-full* API see: `Query Parameter
-Definitions`_.
-
-.. _admonition:: Content-Security-Policy (CSP)
+.. admonition:: Content-Security-Policy (CSP)
 
    This engine needs to allow images from the `data URLs`_ (prefixed with the
-   ``data:` scheme).::
+   ``data:`` scheme)::
 
-     Header set Content-Security-Policy "img-src 'self' data: ;"
+       Header set Content-Security-Policy "img-src 'self' data: ;"
 
-.. _Query Parameter Definitions:
-   https://developers.google.com/custom-search/docs/xml_results#WebSearch_Query_Parameter_Definitions
 .. _data URLs:
    https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs
 """