Update index.rst

Author: RodgerZhu

documents/readthedoc/docs/source/index.rst

@@ -41,7 +41,7 @@ Table of Contents
    Solutions/tdx-hfl/tdx-hfl.md
    Solutions/hfl-tdx-coco/index.md
    Solutions/tdx-encrypted-vfs/index.md
-   Solutions/tdx-encrypted-img/index.md
+   Solutions/td-encrypted-img/index.md
    Solutions/tdx-tf-serving-ppml/index.md
    Solutions/td-encrypte-img/index.md