Chat authentication docs (#116)

* Chat authentication docs

* Update chat auth docs to use Plain.init instead of Plain.setCustomerDetails

* Fix lint

* Include new styling options

_snippets/chat/customization.mdx

@@ -17,15 +17,19 @@ Plain.init({
     },
   ],
 
-  // Optional. The color of your brand which will be used in parts of the Chat as well as the launcher color
-  brandColor: '#000000',
-
   // Optional. The entry point of the Chat, is either 'default' or 'chat'
-  // 'chat' will open the last conversation the user had. (default: 'default')
+  // 'chat' will open the last conversation the user had (default: 'default')
   entryPoint: 'default',
 
-  // Optional. The color scheme of the Chat, is either 'auto', 'light', or 'dark'.
+  // Optional. The color scheme of the Chat, is either 'auto', 'light', or 'dark'
   // 'auto' uses the user's browser preference to decide between light and dark mode (default: 'auto')
   theme: 'light',
+
+  // Optional. Various styling options
+  // Colors can also be passed in this format { light: '#FFFFFF', dark: '#000000' }. Based on the theme chosen by you or browser preference
+  style: {
+    chatButtonColor: '#000000'; // These can also be passed in this foramt { light: '#FFFFFF', dark: '#000000' }
+    chatButtonIconColor: '#FFFFFF';
+  }
 });
 ```

chat/authentication.mdx

@@ -0,0 +1,46 @@
+---
+title: 'Authentication'
+---
+
+## Providing customer details
+
+By default, customers chatting with you will be anonymous. You can pass customer details, if you know them, in the `Plain.init` function call:
+
+```typescript
+Plain.init({
+  // ... Other options
+  customerDetails: {
+    fullName: 'John Doe', // Optional
+    shortName: 'John', // Optional
+    chatAvatarUrl: 'https://picsum.photos/32/32', // Optional
+  },
+});
+```
+
+These details will be shown to you in the Plain app when you are chatting with the customer but they will not be matched to an existing customer even if they have the same details.
+
+## Matching chat users to existing customers
+
+If you want to match the customer to an existing customer in your workspace, you will need to pass their email. To avoid security issues around impersonation you will also need to
+provide the email address hashed using a shared secret. You can generate this secret in the Chat settings page in the Plain app.
+
+Once you have this secret, you can calculate the hash and pass it to the `Plain.init` function:
+
+```typescript
+import * as crypto from 'node:crypto';
+
+const secret = '<YOUR_SECRET>';
+const email = '[email protected]';
+const hmac = crypto.createHmac('sha256', secret);
+hmac.update(email);
+const hash = hmac.digest('hex');
+
+Plain.init({
+  customerDetails: {
+    email: email,
+    emailHash: hash,
+    // If you pass other customer details (e.g. fullName), this will also update their customer details within Plain
+    // If you don't pass any other customer details, we will use their existing details within Plain
+  },
+});
+```

mint.json

@@ -94,7 +94,8 @@
 				{
 					"group": "Chat",
 					"pages": [
-						"chat"
+						"chat",
+						"chat/authentication"
 					]
 				},
 				{