Note about plugin install [skip ci]

netlify.toml

@@ -3,6 +3,12 @@
 	command = "npm run build"
 
 [[plugins]]
+
+	# Opt-in to the Netlify Lighthouse plugin (choose one):
+
+	# 1. via the Netlify UI https://app.netlify.com/sites/eleventy-base-blog/integrations/plugins
+	# 2. Or via `npm install -D @netlify/plugin-lighthouse`
+
 	package = "@netlify/plugin-lighthouse"
 
 	# optional, fails build when a category is below a threshold