Incremented version number, moved and renamed old release-notes.d, and added new release-notes.md

Summary: Incremented version number, moved and renamed old release-notes.d, and added new release-notes.md

Test Plan: make check

Reviewers: deadalnix, jasonbcox, Fabien, O1 Bitcoin ABC, #bitcoin_abc

Reviewed By: jasonbcox, O1 Bitcoin ABC, #bitcoin_abc

Subscribers: schancel

Differential Revision: https://reviews.bitcoinabc.org/D2778