docs[minor]: Swap gtag for supabase (#18937)

Added deps:
- `@supabase/supabase-js` - for sending inserts
- `supabase` - dev dep, for generating types via cli
- `dotenv` for loading env vars

Added script:
- `yarn gen` - will auto generate the database schema types using the
supabase CLI. Not necessary for development, but is useful. Requires
authing with the supabase CLI (will error out w/ instructions if you're
not authed).

Added functionality:
- pulls users IP address (using a free endpoint: `https://api.ipify.org`
so we can filter out abuse down the line)

TODO:
- [x] add env vars to vercel

docs/docusaurus.config.js

@@ -4,7 +4,7 @@
 // Note: type annotations allow type checking and IDEs autocompletion
 // eslint-disable-next-line import/no-extraneous-dependencies
 const { ProvidePlugin } = require("webpack");
-const path = require("path");
+require("dotenv").config();
 
 const baseLightCodeBlockTheme = require("prism-react-renderer/themes/vsLight");
 const baseDarkCodeBlockTheme = require("prism-react-renderer/themes/vsDark");
@@ -335,12 +335,13 @@ const config = {
       src: "https://www.googletagmanager.com/gtag/js?id=G-9B66JQQH2F",
       async: true,
     },
-    {
-      src: "https://www.googletagmanager.com/gtag/js?id=G-WFT0J048RF",
-      async: true,
-    }
   ],
-  
+
+  customFields: {
+    NEXT_PUBLIC_SUPABASE_PUBLIC_KEY:
+      process.env.NEXT_PUBLIC_SUPABASE_PUBLIC_KEY,
+    NEXT_PUBLIC_SUPABASE_URL: process.env.NEXT_PUBLIC_SUPABASE_URL,
+  },
 };
 
 module.exports = config;