Update new-release.md after 5.11.0 release
Notable changes are:
- removing some references to PDFs we no longer use
- updating who is tagged for some tasks
- adding checkboxes for some tasks
- cleaning up the superbuild MR steps
GitLab update will be applied on June 28th, between 8am and 10:30am, EDT (UTC-04:00). This site may have intermittent delays during that time.
Notable changes are: