Describe the bug

sphinx-build -W -b html -d /tmp/doctrees docs docs/html
Warning, treated as error:
node class 'meta' is already registered, its visitors will be overridden

How to Reproduce

build documentation

Expected behavior

No warning

Your project

source is not available

Screenshots

No response

OS

Centos7

Python version

Python 3.8

Sphinx version

sphinx==2.3.1

Sphinx extensions

Extra tools

No response

Additional context

index.rst:

Welcome to project's documentation!

.. toctree::
:maxdepth: 2
:caption: Contents:

syntax_introduction

Indices and tables

• :ref:genindex
• :ref:modindex
• :ref:search