Add Algorithm::SpiralMatrix to ecosystem

See https://github.com/mj41/Algorithm-SpiralMatrix

Author: mj41

META.list

@@ -867,3 +867,4 @@ https://raw.githubusercontent.com/kjkuan/Proc-Feed/master/META6.json
 https://raw.githubusercontent.com/dmaestro/Module-Pod/master/META6.json
 https://raw.githubusercontent.com/oposs/jsonhound/master/META6.json
 https://gitlab.com/pheix/lzw-revolunet-perl6/raw/master/META6.json
+https://raw.githubusercontent.com/mj41/Algorithm-SpiralMatrix/master/META6.json