[doc] remove flattr from readme

README.rst

 
 See the `documentation <https://asciimoo.github.io/searx>`__ and the `wiki <https://github.com/asciimoo/searx/wiki>`__ for more information.
 
-|Flattr searx|
 |OpenCollective searx backers|
 |OpenCollective searx sponsors|
 
 -  `twitter <https://twitter.com/Searx_engine>`__
 -  IRC: #searx @ freenode
 
-.. |Flattr searx| image:: http://api.flattr.com/button/flattr-badge-large.png
-   :target: https://flattr.com/submit/auto?user_id=asciimoo&url=https://github.com/asciimoo/searx&title=searx&language=&tags=github&category=software
-
 
 .. |OpenCollective searx backers| image:: https://opencollective.com/searx/backers/badge.svg
    :target: https://opencollective.com/searx#backer