Update release-notes.md

Fixed formatting issues with pre texts
Merge pull request #103 from davidalger/patch-1

Update release-notes.md
Merge branch 'develop' of github.com:magento/devdocs into develop
PR: Merge davidalger's changes and also add one more indent-based pre fix
Merge pull request #105 from magento/develop

Accepted all of davidalger's changes and made one more. There was one more place where a <pre> tag could be replaced by an indent.