Fix incorrect package name and filename in scripts/js-api/README.md (#56362)

Summary:
Two documentation errors in `scripts/js-api/README.md`:

1. **Wrong link text** (line 22): The link for the Flow-to-TypeScript converter reads `[flow-api-extractor](https://www.npmjs.com/package/flow-api-translator)` but the package name is `flow-api-translator`, not `flow-api-extractor`. The link URL was correct but the visible text was misleading.

2. **Wrong filename** (line 76): The Public API snapshot section refers to the file as `ReactNative.d.ts`, while the actual file committed to the repo is `ReactNativeApi.d.ts`. The correct name is already used earlier in the same document (line 16 and line 41).

Fixes #55667
Fixes #55668

## Changelog:

[General] [Fixed] - Fix incorrect package name and output filename in scripts/js-api/README.md

Pull Request resolved: #56362

Test Plan: Documentation-only change. Verified the link URL and the actual file name at `packages/react-native/ReactNativeApi.d.ts`.

Reviewed By: huntie

Differential Revision: D100761759

Pulled By: cortinico

fbshipit-source-id: 8a30ca1a5f35c9491c2ad4c94ae20da4621cb5a7

Author: Nedunchezhiyan-M

scripts/js-api/README.md

@@ -19,7 +19,7 @@ Snapshot file of the public API shape, used by maintainers\
 
 `yarn build-types` makes use of the following dependencies, composed with other pre/post transformation steps and dependency resolution.
 
-- Flow → TypeScript conversion: [flow-api-extractor](https://www.npmjs.com/package/flow-api-translator)
+- Flow → TypeScript conversion: [flow-api-translator](https://www.npmjs.com/package/flow-api-translator)
 - TypeScript → (initial) API rollup: [@microsoft/api-extractor](https://api-extractor.com/)
 
 ## Usage
@@ -73,7 +73,7 @@ Directory providing TypeScript user types for the `react-native` package, distri
 
 ### Public API snapshot
 
-`ReactNative.d.ts`
+`ReactNativeApi.d.ts`
 
 Provides a human-readable, maintainable reference of the React Native's public JavaScript API, optimized for developers and diff tooling.