docs: update documents

Author: mizdra

docs/api/inline-fixture-files.createiff.md

@@ -9,7 +9,7 @@ Create fixtures in the specified directory.
 **Signature:**
 
 ```typescript
-export type CreateIFF = <const T extends Directory, U extends Directory = {}>(directory: T, options?: CreateIFFOptions | undefined, __INTERNAL__prevIFF?: CreateIFFResult<U>) => Promise<CreateIFFResult<MergeDirectory<U, T>>>;
+export type CreateIFF = <const T extends Directory, U extends Directory = {}>(directory: T, options?: CreateIFFOptions, __INTERNAL__prevIFF?: CreateIFFResult<U>) => Promise<CreateIFFResult<MergeDirectory<U, T>>>;
 ```
 **References:** [Directory](./inline-fixture-files.directory.md)<!-- -->, [CreateIFFOptions](./inline-fixture-files.createiffoptions.md)<!-- -->, [CreateIFFResult](./inline-fixture-files.createiffresult.md)
 

docs/api/inline-fixture-files.createiffresult.fork.md

@@ -9,15 +9,15 @@ Change the root directory and take over the fixture you created.
 **Signature:**
 
 ```typescript
-fork<const U extends Directory>(additionalDirectory: U, forkOptions?: ForkOptions | undefined): Promise<CreateIFFResult<MergeDirectory<T, U>>>;
+fork<const U extends Directory>(additionalDirectory: U, forkOptions?: ForkOptions): Promise<CreateIFFResult<MergeDirectory<T, U>>>;
 ```
 
 ## Parameters
 
 |  Parameter | Type | Description |
 |  --- | --- | --- |
 |  additionalDirectory | U | The definition of fixtures to be added. |
-|  forkOptions | [ForkOptions](./inline-fixture-files.forkoptions.md) \| undefined | _(Optional)_ The fork options. |
+|  forkOptions | [ForkOptions](./inline-fixture-files.forkoptions.md) | _(Optional)_ The fork options. |
 
 **Returns:**