[README] Keep only badges that make sense on PyPI

README.rst

 .. vim: set fileencoding=utf-8 :
 
-.. image:: https://img.shields.io/badge/docs-stable-yellow.svg
-   :target: https://www.idiap.ch/software/bob/docs/bob/bob.devtools/stable/index.html
-.. image:: https://img.shields.io/badge/docs-latest-orange.svg
+.. image:: https://img.shields.io/badge/docs-current-green.svg
    :target: https://www.idiap.ch/software/bob/docs/bob/bob.devtools/master/index.html
 .. image:: https://gitlab.idiap.ch/bob/bob.devtools/badges/master/pipeline.svg
    :target: https://gitlab.idiap.ch/bob/bob.devtools/commits/master
@@ -10,8 +8,6 @@
    :target: https://gitlab.idiap.ch/bob/bob.devtools/commits/master
 .. image:: https://img.shields.io/badge/gitlab-project-0000c0.svg
    :target: https://gitlab.idiap.ch/bob/bob.devtools
-.. image:: https://img.shields.io/pypi/v/bob.devtools.svg
-   :target: https://pypi.python.org/pypi/bob.devtools
 
 
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