Feat(comment): add gitalk

[ElderJames]

Contributing rules

• Fork the repo and create your branch from canary. Then be sure to put the canary branch as the target for your pull request.
• Please be sure to follow the contributing guidelines, especially for commit message
• Remove the Contributing rules part from this description
• Fill out the other parts from this description

If you don't do so, we might change your pull request's title and using squash to merge your changed.

What kind of change does this PR introduce? (check one with "x")

• Bug fix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

Does this PR introduce a breaking change? (check one with "x")

• Yes
• No

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Description

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Verification steps

setup the settings in config file

    gitalk_owner: # git repo of the hexo
    gitalk_repo: # git repo's owner
    gitalk_client_id: # github app client id 
    gitalk_client_secret : # github app client secret