[cashtab-docs] remove BCH logo from twitter card
[cashtab-docs] remove BCH logo from twitter card

Summary: Remove BCH logo from twitter card

Test Plan: inspect new image, make sure you do not see a BCH logo

Reviewers: #bitcoin_abc, majcosta, Mengerian

Reviewed By: #bitcoin_abc, majcosta, Mengerian

Subscribers: Mengerian

Differential Revision: https://reviews.bitcoinabc.org/D9209

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