vault: Install and enable the "Vault Nickname" plugin

So that in Obsidian I can distinguish between identically-named
vaults from the maine Tasks repo and my fork.

Author: claremacrae

resources/sample_vaults/Tasks-Demo/.obsidian/community-plugins.json

@@ -17,5 +17,6 @@
   "js-engine",
   "table-editor-obsidian",
   "reveal-active-file-button",
-  "obsidian-meta-bind-plugin"
+  "obsidian-meta-bind-plugin",
+  "vault-nickname"
 ]