[ImageMagick] ImageMagick 6.8.6-3
[leveldb] leveldb 1.12.0
[mroonga] mroonga 3.05
Add installation guidance, which is copied from the Homebrew's mroonga package.
(https://github.com/mroonga/homebrew/blob/master/mroonga.rb)
Merge branch 'master' into main
[main] Update PortIndex.