doc: set module version 72 to node 12

Clearly state the modules version 72 is official node 12, similar as it
is done for other major node versions.

PR-URL: #29877
Reviewed-By: Richard Lau <[email protected]>
Reviewed-By: Beth Griggs <[email protected]>
Reviewed-By: Jiawen Geng <[email protected]>
Reviewed-By: David Carlier <[email protected]>
Reviewed-By: Myles Borins <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>

Author: Flarna

doc/abi_version_registry.json

@@ -1,13 +1,13 @@
 {
   "NODE_MODULE_VERSION": [
-    { "modules": 79, "runtime": "node", "variant": "v8_7.8", "versions": "13.0.0-pre" },
+    { "modules": 79, "runtime": "node",     "variant": "v8_7.8",               "versions": "13.0.0-pre" },
     { "modules": 78, "runtime": "node",     "variant": "v8_7.7",               "versions": "13.0.0-pre" },
     { "modules": 77, "runtime": "node",     "variant": "v8_7.6",               "versions": "13.0.0-pre" },
     { "modules": 76, "runtime": "electron", "variant": "electron",             "versions": "8" },
     { "modules": 75, "runtime": "electron", "variant": "electron",             "versions": "7" },
     { "modules": 74, "runtime": "node",     "variant": "v8_7.5",               "versions": "13.0.0-pre" },
     { "modules": 73, "runtime": "electron", "variant": "electron",             "versions": "6" },
-    { "modules": 72, "runtime": "node",     "variant": "v8_7.4",               "versions": "12.0.0-pre" },
+    { "modules": 72, "runtime": "node",     "variant": "node",                 "versions": "12" },
     { "modules": 71, "runtime": "node",     "variant": "v8_7.3",               "versions": "12.0.0-pre" },
     { "modules": 70, "runtime": "electron", "variant": "electron",             "versions": "5" },
     { "modules": 69, "runtime": "electron", "variant": "electron",             "versions": "^4.0.4" },