fix(docs): remove outdated travis build status badge (#291)

README.rst

@@ -1,4 +1,4 @@
-|Build| |PyPI version| |Docs badge| |License|
+|PyPI version| |Docs badge| |License|
 
 sphinx-hoverxref
 ================
@@ -51,9 +51,6 @@ Check out the full documentation at https://sphinx-hoverxref.readthedocs.io/
 .. _Sphinx: https://www.sphinx-doc.org/
 
 
-.. |Build| image:: https://travis-ci.org/readthedocs/sphinx-hoverxref.svg?branch=master
-   :target: https://travis-ci.org/readthedocs/sphinx-hoverxref
-   :alt: Build status
 .. |PyPI version| image:: https://img.shields.io/pypi/v/sphinx-hoverxref.svg
    :target: https://pypi.org/project/sphinx-hoverxref
    :alt: Current PyPI version