Only warn once about conceallevel

See #617.

Author: epwalsh

lua/obsidian/ui.lua

@@ -626,7 +626,7 @@ M.setup = function(workspace, ui_opts)
       local conceallevel = vim.opt_local.conceallevel:get()
 
       if conceallevel < 1 or conceallevel > 2 then
-        log.warn(
+        log.warn_once(
           "Obsidian additional syntax features require 'conceallevel' to be set to 1 or 2, "
             .. "but you have 'conceallevel' set to '%s'.\n"
             .. "See https://github.com/epwalsh/obsidian.nvim/issues/286 for more details.\n"