.gitlab/issue_templates/*.md:
Set the title in all issue templates.
Add an explicit identifier (MODIFY) to all parts of the template where
modification is required by the user.
Extend the main key removal template by more specific steps for the main
key holders and keyring maintainer.
.gitlab/issue_templates/Remove Packager Key.md:
Add a subsection for main key holders that specifically tracks the
status on the key signature revocation.
.gitlab/issue_templates/New Packager Key.md:
Extend the Checks section by a subsection specifically for main key
holders, that ensures all main key holders have validated and signed a
new packager key (with the help of checkboxes).
Clarify wording in the keyring maintainer related subsection.
.gitlab/issue_templates/New Main Key.md:
Add issue template for adding a new main key.
.gitlab/issue_templates/New Packager Key.md:
Add issue template for adding a new packager key.
.gitlab/issue_templates/Remove Main Key.md:
Add issue template for removing a main key.
.gitlab/issue_templates/Remove Packager Key.md:
Add issue template for removing a packager key.
