chore: record the two new derivable dumps

The MAME 0.289 device sets made two more catalogued dumps derivable
from held ones: derivable.json lists 67, and the tools page now says
so.

derivable.json

@@ -321,12 +321,24 @@
     ],
     "transform": "second half"
   },
+  "b3806edacb3362fc16a154ce1eeec5bf5bc24789": {
+    "from": [
+      "bios/Commodore/Amiga/amiga-os-310-a4000t.rom"
+    ],
+    "transform": "even words, byte-swapped"
+  },
   "b8800f5f909298109ea69690b1b8523fa22ddb37": {
     "from": [
       "bios/Commodore/Amiga/amiga-os-310-a1200.rom"
     ],
     "transform": "even words, byte-swapped"
   },
+  "cd7a706c431b04d87814d3a2d8b397100cf44c0c": {
+    "from": [
+      "bios/Commodore/Amiga/amiga-os-310-a4000t.rom"
+    ],
+    "transform": "odd words, byte-swapped"
+  },
   "d234a031caf59a0f66871f2babe1644783e66cf7": {
     "from": [
       "bios/Commodore/C128/vice/C128/kernalfr"

wiki/tools.md

@@ -800,7 +800,7 @@ marks a missing entry DERIVABLE when a held file produces its sha1 by halving,
 quartering, splitting into even and odd bytes or 16-bit words (byte-swapped
 or not), swapping bytes, mirroring, or joining two files of one directory.
 The Amiga Kickstart chip pairs and TOSEC's split C64 and VES ROMs are found
-this way: 65 entries on the current snapshots, recorded in `derivable.json`
+this way: 67 entries on the current snapshots, recorded in `derivable.json`
 by pipeline step 1b.
 
 | Catalog | Acquisition | Notes |