Add tooltips to documentation cross-references

docs/conf.py

@@ -27,6 +27,7 @@ sys.path.insert(0, path.dirname(path.dirname(__file__)))
 # Add any Sphinx extension module names here, as strings. They can be extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 extensions = [
+    'hoverxref.extension',
     'notfound.extension',
     'scrapydocs',
     'sphinx.ext.autodoc',

docs/requirements.txt

@@ -1,3 +1,4 @@
 Sphinx>=2.1
+sphinx-hoverxref
 sphinx-notfound-page
 sphinx_rtd_theme