update news and fix the links of the readme

NEWS.rst

@@ -2,6 +2,6 @@
 Changelog
 =========
 
-1.0
----
+15.0.1.0.0
+----------
 
@@ -7,2 +7,2 @@
 
-Initial version.
+Migration to Odoo 15

README.rst

@@ -5,7 +5,8 @@
 .. |coverage| image:: https://orus.io/xcg/odoo-modules/base_context/badges/branch/15.0/coverage.svg
     :target: https://orus.io/xcg/odoo-modules/base_context/-/pipelines?ref=branch/15.0
     :alt: Coverage report
-.. |pylint| image:: badges/pylint.svg
+.. the image is updated by the CI when building the documentation
+.. |pylint| image:: .badges/pylint.svg
     :target: https://orus.io/xcg/odoo-modules/base_context/-/pipelines?ref=branch/15.0
     :alt: pylint score
 .. |maturity| image:: .badges/maturity.svg