[e.cash] Changing "Etokens" copy on Core-tech page

Summary: Adding NFT to the copy and removing a comma for grammar consistency.

Test Plan: visit e.cash/core-tech, scroll down to eTokens and verify copy.

Reviewers: #bitcoin_abc, Mengerian

Reviewed By: #bitcoin_abc, Mengerian

Differential Revision: https://reviews.bitcoinabc.org/D16140