Merge pull request #35595 from Expensify/Rory-GoogleSignInDocs

[No QA] Improve Google Sign In documentation

contributingGuides/APPLE_GOOGLE_SIGNIN.md

@@ -259,12 +259,33 @@ if (CONFIG.ENVIRONMENT === CONST.ENVIRONMENT.DEV) {
 }
 ```
 
-#### Port requirements
+#### Host/Port requirements
 
 Google allows the web app to be hosted at localhost, but according to the
 current Google console configuration for the Expensify client ID, it must be
 hosted on port 8082.
 
+Also note that you'll need to update the webpack.dev.js config to change `host` from `dev.new.expensify.com` to `localhost` and server type from `https` to `http`. The reason for this is that Google Sign In allows localhost, but `dev.new.expensify.com` is not a registered Google Sign In domain.
+
+```diff
+diff --git a/config/webpack/webpack.dev.js b/config/webpack/webpack.dev.js
+index e28383eff5..b14f6f34aa 100644
+--- a/config/webpack/webpack.dev.js
++++ b/config/webpack/webpack.dev.js
+@@ -44,9 +44,9 @@ module.exports = (env = {}) =>
+                 ...proxySettings,
+                 historyApiFallback: true,
+                 port,
+-                host: 'dev.new.expensify.com',
++                host: 'localhost',
+                 server: {
+-                    type: 'https',
++                    type: 'http',
+                     options: {
+                         key: path.join(__dirname, 'key.pem'),
+                         cert: path.join(__dirname, 'certificate.pem'),
+```
+
 ### Desktop
 
 #### Set Environment to something other than "Development"