Fixed wrapping of cell content in readthedocs style

The readthedocs style for sphinx has an issue where it does not auto
wrap text in table cells. This results in very long cells with a
vertical scrollbar.

This adds a css style sheet to fix this wrapping issue.

Signed-off-by: Claudius Heine <ch@denx.de>

docs/_static/theme_overrides.css

@@ -0,0 +1,13 @@
+/* override table width restrictions */
+@media screen and (min-width: 767px) {
+
+   .wy-table-responsive table td {
+      /* !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;
+   }
+}