fix: clear up language in update notification for AstroNvim

lua/astronvim/plugins/_astrocore.lua

@@ -10,7 +10,7 @@ return {
  vim.schedule(
  function()
  require("astrocore").notify(
- "Stable plugin versions may have been updated\nRun `:Lazy update` again to get these updates.",
+ "Pinned versions of core plugins may have been updated\nRun `:Lazy update` again to get these updates.",
  vim.log.levels.WARN
  )
  end