Wrap paths in codeblocks in release-process.md

Summary: These will render nicely and paths containing * break vim's syntax highlighter without the codeblock wrapper present.

Test Plan: Read it.

Reviewers: #bitcoin_abc, deadalnix, Fabien

Reviewed By: #bitcoin_abc, deadalnix, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D4890