Formatting for the branching doc.

Author: griwes

doc/branching.md

@@ -21,22 +21,22 @@ versions don't directly map to any CUDA Toolkit version.
 | v1.8.3-2          | 8.0           |
 | v1.8.2            | 7.0           |
 | v1.8.1            | 7.0           |
-| v1.8.0            | N/A           |
+| v1.8.0            | *N/A*         |
 | v1.7.2            | 6.5           |
 | v1.7.1            | 6.0           |
 | v1.7.0            | 5.5           |
-| v1.6.0            | N/A           |
+| v1.6.0            | *N/A*         |
 | v1.5.3            | 5.0           |
 | v1.5.2            | 4.2           |
 | v1.5.1            | 4.1           |
-| v1.5.0            | N/A           |
+| v1.5.0            | *N/A*         |
 | v1.4.0            | 4.0           |
 | v1.3.0            | 3.2           |
 | v1.2.1            | 3.1           |
-| v1.2.0            | N/A           |
-| v1.1.1            | N/A           |
-| v1.1.0            | N/A           |
-| v1.0.0            | N/A           |
+| v1.2.0            | *N/A*         |
+| v1.1.1            | *N/A*         |
+| v1.1.0            | *N/A*         |
+| v1.0.0            | *N/A*         |
 
 ## Repositories