schema/config-linux: Check swappiness for zero to 100 range

Catch the JSON Schema up with e73cd70 (Make Linux memory allocations
int64 not uint64, 2017-06-23, opencontainers#876), which carried the kernel's 0 to
100 range into the spec.

Signed-off-by: W. Trevor King <[email protected]>

Author: wking

schema/config-linux.json

@@ -188,7 +188,7 @@
                             },
                             "swappiness": {
                                 "id": "https://opencontainers.org/schema/bundle/linux/resources/memory/swappiness",
-                                "$ref": "defs.json#/definitions/uint64"
+                                "$ref": "defs.json#/definitions/percent"
                             },
                             "disableOOMKiller": {
                                 "id": "https://opencontainers.org/schema/bundle/linux/resources/memory/disableOOMKiller",