edk2-lib\readme.md : Update required to reflect the changes from email patch to GitHub PR Review process

[jpshivakavi]

The following sections of the readme.md file needs to be updated as per the GitHub PR review process requirements.

Sample Change Description / Commit Message
From: Contributor Name <[email protected]>
Subject: [Repository/Branch PATCH] Pkg-Module: Brief-single-line-summary

Full-commit-message

Signed-off-by: Contributor Name <[email protected]>

<<Notes for sample patch email>>
• The first line of commit message is taken from the email's subject line following [Repository/Branch PATCH]. The remaining portion of the commit message is the email's content.
• git format-patch is one way to create this format

<<Definitions for sample patch email>>