[e.cash] Added localeCash to "use-ecash" page

Summary:
Added localeCash service to use-ecash, uploaded localeCash.png image and fixed case naming issue
of localecash.png file

Test Plan: visit e.cash/use-ecash and see if everything works correctly

Reviewers: #bitcoin_abc, Mengerian

Reviewed By: #bitcoin_abc, Mengerian

Subscribers: Mengerian

Differential Revision: https://reviews.bitcoinabc.org/D17766