doc/conf.py: add 'sphinxcontrib.jquery'

This works around cases where Sphinx does not add jQuery automatically
on some local setups <readthedocs/sphinx_rtd_theme#1452>.

doc/conf.py

@@ -13,7 +13,12 @@
     subprocess.call('doxygen')
 
 # Add any Sphinx extension module names here, as strings.
-extensions = ['sphinx.ext.todo', 'sphinx.ext.viewcode', 'breathe']
+extensions = [
+    'sphinx.ext.todo',
+    'sphinx.ext.viewcode',
+    'sphinxcontrib.jquery',
+    'breathe',
+]
 
 # Breathe configuration
 breathe_projects = {"libkres": "doxyxml"}