Setup repo

[mkurz]

• Discord webhook
• Rename to play-memcached?
• Change groupId to org.playframework?
• https://github.com/VirtusLab/scala-steward-repos/blob/main/repos-github.md (depends on previous todos)
• Overhaul README
• GitHub actions Workflows (also see Switch from travis to Github actions + release by tag  #79)
• Branch protection(s)
• License