[e.cash] Add button and bip70 label to wallets page
Summary: Slightly changed the copy at the beginning and added a button to our wallet guide. Also added the BIP-70 label to wallets that support it.
Test Plan: Visit e.cash/wallets and check copy, scroll down and check labels. Click the "Wallet Guide" button to see if it leads to the blog post.
Reviewers: #bitcoin_abc, bytesofman
Reviewed By: #bitcoin_abc, bytesofman
Subscribers: bytesofman, PiRK
Differential Revision: https://reviews.bitcoinabc.org/D16679