feat: add x-tombi-additional-key-label (SchemaStore#5014)

Author: ya7010

CONTRIBUTING.md

@@ -334,6 +334,10 @@ Used by: `tombi-toml/tombi`. See [this](https://tombi-toml.github.io/tombi/docs/
 
 Used by: `tombi-toml/tombi`. See [this](https://tombi-toml.github.io/tombi/docs/json-schema#x-tombi-string-formats) for details.
 
+**`x-tombi-additional-key-label`**
+
+Used by: `tombi-toml/tombi`. See [this](https://tombi-toml.github.io/tombi/docs/json-schema#x-tombi-additional-key-label) for details.
+
 **`x-intellij-language-injection`**
 
 Used by Intellij.

cli.js

@@ -507,6 +507,7 @@ async function ajvFactory(
     'x-tombi-array-values-order-by',
     'x-tombi-table-keys-order',
     'x-tombi-string-formats',
+    'x-tombi-additional-key-label',
     'x-intellij-language-injection',
     'x-intellij-html-description',
     'x-intellij-enum-metadata',