Remove deadlinks from home page

source/javascripts/instances.json

@@ -5,11 +5,6 @@
       "description": "The oldest public, generalistic instance for people to see what Plume is like",
       "url": "https://fediverse.blog"
     },
-    {
-      "name": "Plume on Mastodon.Host",
-      "description": "A Plume instance served by the team behind Mastodon.host",
-      "url": "https://plume.mastodon.host"
-    },
     {
       "name": "Lorem.Club",
       "description": "A welcoming Plume instance for everyone, run by enthusiasts",
@@ -33,11 +28,6 @@
       "name": "Les Nouvelles d'Ombreport",
       "url": "https://plume.ombreport.info"
     },
-    {
-      "name": "Plume OpenAlgeria",
-      "description": "A Plume instance, by the OpenAlgeria team",
-      "url": "https://plume.social"
-    },
     {
       "name": "catlife.drycat.fr",
       "url": "https://catlife.drycat.fr"