Add CSS style override for RTD to make tables use word wrapping

(imported from commit 29007c052dd7048eaf86388a6a9715fc13f102b5)

docs/_static/theme_overrides.css

@@ -0,0 +1,10 @@
+/* override table width restrictions */
+.wy-table-responsive table td, .wy-table-responsive table th {
+    /* !important prevents the common CSS stylesheets from
+       overriding this as on RTD they are loaded after this stylesheet */
+    white-space: normal !important;
+}
+
+.wy-table-responsive {
+    overflow: visible !important;
+}