chore: Update docs generation workflow and standardize README filenames

- Update .NET version from 8 to 9 in GitHub Actions workflow
- Change docfx action from CaseyHofland/docfx-unitypackage to Bli-AIk/docfx-unitypackage
- Rename readme.md and its meta file to uppercase README.md for consistency

Author: Bli-AIk

.github/workflows/generate-docs.yml

@@ -18,14 +18,14 @@ jobs:
         with:
           submodules: true
 
-      - name: Setup .NET 8
+      - name: Setup .NET 9
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: '8.0'
+          dotnet-version: '9.0'
 
 
       - name: Build
-        uses: CaseyHofland/docfx-unitypackage@v1
+        uses: Bli-AIk/docfx-unitypackage@v1
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}