Replacing Twitter with X

[1Shubham7]

• Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  docs update

• What is the current behavior? (You can also link to an open issue here)
  We have a Twitter logo.

solves a part of #533

• What is the new behavior (if this is a feature change)?
  I have replaced the twitter logo with X

Closes #444
Closes #390

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)
  no

• Other information:

[1Shubham7]

@fisherxu @wbc6080, should we also replace Twitter as text with X in various parts of the docs? example

[wbc6080]

Good job!
/lgtm

[Shelley-BaoYue]

Thanks for your contributions!
/lgtm

[Shelley-BaoYue]

/approve

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