Add isSupported function support for language (#17331)

Co-authored-by: fisker Cheung <lionkay@gmail.com>
Co-authored-by: fisker <lionkay@gmail.com>

docs/api.md

@@ -124,6 +124,7 @@ The support information looks like this:
     filenames?: string[];
     linguistLanguageId?: number;
     vscodeLanguageIds?: string[];
+    isSupported?(file: string): boolean;
   }>;
 }
 ```

docs/plugins.md

@@ -70,7 +70,7 @@ Strings provided to `plugins` are ultimately passed to [`import()` expression](h
 - [`prettier-plugin-sql-cst`](https://github.com/nene/prettier-plugin-sql-cst) by [**@nene**](https://github.com/nene)
 - [`prettier-plugin-solidity`](https://github.com/prettier-solidity/prettier-plugin-solidity) by [**@mattiaerre**](https://github.com/mattiaerre)
 - [`prettier-plugin-svelte`](https://github.com/sveltejs/prettier-plugin-svelte) by [**@sveltejs**](https://github.com/sveltejs)
-- [`prettier-plugin-toml`](https://github.com/bd82/toml-tools/tree/master/packages/prettier-plugin-toml) by [**@bd82**](https://github.com/bd82)
+- [`prettier-plugin-toml`](https://github.com/un-ts/prettier/tree/master/packages/toml) by [**@JounQin**](https://github.com/JounQin) and [**@so1ve**](https://github.com/so1ve)
 
 ## Developing Plugins