[e.cash] Changing the Main Copy of the "Avalanche" section in Core-Tech.

Summary: Adding more benefits of Avalanche and removing mention of BCH forks.

Test Plan: visit e.cash/core-tech scroll down to Avalanche and double check copy.

Reviewers: #bitcoin_abc, Mengerian

Reviewed By: #bitcoin_abc, Mengerian

Subscribers: Mengerian

Differential Revision: https://reviews.bitcoinabc.org/D16139