Docs: Fix CSS theme style issue

The Sphinx theme used to render the documentation
is affected by a bug which causes text in table cells
not to wrap. This patch overrides the CSS configuration
of the theme to allow text wrapping in tables.

Change-Id: I68acfa92d45f0f3452be721480a8ceec60422b2a
Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
diff --git a/docs/_static/css/custom.css b/docs/_static/css/custom.css
index d975dc0..c50f05c 100644
--- a/docs/_static/css/custom.css
+++ b/docs/_static/css/custom.css
@@ -8,3 +8,15 @@
 .wy-nav-content {
   max-width: 85% !important;
 }
+
+/* Avoid tables not wrapping text */
+@media screen and (min-width: 767px) {
+
+   .wy-table-responsive table td {
+      white-space: normal !important;
+   }
+
+   .wy-table-responsive {
+      overflow: visible !important;
+   }
+}