Remove manifest documentation

The manifest repository was migrated in the oniro repository along with
its documentation. The existing references to it are now obsolete.

Signed-off-by: Andrei Gherzan <andrei@gherzan.com>

ci/index.rst

@@ -15,7 +15,6 @@ important elements are described below.
 .. toctree::
    :maxdepth: 1
 
-   manifest
    meta-ohos
    xts-acts
    docs

ci/manifest.rst

-.. SPDX-FileCopyrightText: Huawei Inc.
-..
-.. SPDX-License-Identifier: CC-BY-4.0
-
-The manifest Repository
-=======================
-
-Refer to the section about :doc:`CI in manifest repository
-</repos/manifest/ci/index>`.

index.rst

@@ -28,7 +28,6 @@ daily life.
    oniro/index
    contributing/index
    ci/index
-   repos/index
    building-project-documentation
    ip-policy/index
    security/index

repos/index.rst

-.. SPDX-FileCopyrightText: Huawei Inc.
-..
-.. SPDX-License-Identifier: CC-BY-4.0
-
-.. include:: ../definitions.rst
-
-Git Repositories
-================
-
-|main_project_name| development is organized through a set of ``git`` repositories.
-Some of those are documented below.
-
-.. toctree::
-   :maxdepth: 1
-
-   manifest/index

repos/manifest

-../../.repo/manifests/docs/
\ No newline at end of file