docs: fix word wrap in tables

The sphinx-rtd-theme currently disables word wrap in table cells due to
a bug: readthedocs/sphinx_rtd_theme#1505
This is fixed by overriding the CSS and enabling word wrapping.

docs/source/_static/custom.css

@@ -0,0 +1,9 @@
+@import 'css/theme.css';
+
+/* Fix white-space wrapping in tables.
+ * See https://github.com/readthedocs/sphinx_rtd_theme/issues/1505
+ * This is included via html_static_path and html_style in conf.py
+ */
+.wy-table-responsive table td {
+    white-space: normal;
+}

docs/source/conf.py

@@ -96,7 +96,12 @@ def setup(app):
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".
-html_static_path = []
+html_static_path = ['_static']
+
+# Fix white-space wrapping in tables.
+# See https://github.com/readthedocs/sphinx_rtd_theme/issues/1505
+# Once fixed, this can be removed and '_static' can be removed from html_static_path.
+html_style = 'custom.css'
 
 # Configuration of the 'Edit on GitHub' button at the top right.
 html_context = {