Docs: reformat github driver docs

Change-Id: Icb74dc39714b6efac4fcc1f1d44772982a236b35
diff --git a/doc/source/admin/drivers/gerrit.rst b/doc/source/admin/drivers/gerrit.rst
index 8467ed8..ac42bd3 100644
--- a/doc/source/admin/drivers/gerrit.rst
+++ b/doc/source/admin/drivers/gerrit.rst
@@ -89,7 +89,7 @@
 
 .. attr:: pipeline.trigger.<gerrit source>
 
-   The dictionary passed to the Gerrit pipeline `trigger` attribute
+   The dictionary passed to the Gerrit pipeline ``trigger`` attribute
    supports the following attributes:
 
    .. attr:: event