feat(footer_sns): add segmentfault

[cntanglijun]

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.
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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

Add a new sns icon for segmentfault

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Verification steps

No verification steps.

[neoFelhz]

Thank you for your contribututions!
Anyway, please using canary branch as base branch when open a new PR. canary branch is used to test new feat code.

[neoFelhz]

Now I set your branch to canary.

[AkarinServer]

@cntanglijun 你的sf footer请尽量按照sf官方定义的logo来

[AkarinServer]

Please change all picture format to svg expect for yours one
请将所有的png后缀更改为svg，因为我们已经全面采用svg格式的icon了，当然你的pr可以保留为png格式

[neoFelhz]

Now we are using svg now. Please update your sns icon as svg format.