fix: update enable.md

Author: MichaelCurrin

cheatsheets/jekyll/plugins/enable.md

@@ -9,7 +9,7 @@ For local development and use outside of GH Pages, it is sufficient to add a plu
 group :jekyll_plugins do
   gem "jekyll-feed"
   gem "jekyll-sitemap", "~> 1.4"
-  gem "jekyll-seo-tag, "~> 2.7.1"
+  gem "jekyll-seo-tag", "~> 2.7.1"
 end
 ```