Adding docs for message bridge (#1230)

* document message bridge

* Added example

---------

Co-authored-by: Shane Osbourne <[email protected]>

Author: shakyShane

.gitignore

@@ -4,7 +4,7 @@ node_modules/
 .env
 .build/
 build/
-docs/
+/docs
 /screens
 test-results/
 playwright-report/

injected/docs/message-bridge.md

@@ -0,0 +1,93 @@
+---
+title: Message Bridge
+---
+
+## Description 
+
+Message Bridge creates a communication between a website and a browser. It sends and receives messages that conform 
+to our Messaging standard (eg: it's not a new format!)
+
+- Related Privacy Configuration [feature file](https://github.com/duckduckgo/privacy-configuration/blob/main/features/message-bridge.json)
+- Message formats: {@link "Messaging Schema"}
+
+
+## Integration guide
+
+## Step 1: add `messageSecret` to `$USER_PREFERENCES$` 
+
+This feature requires the following to be serialized into `$USER_PREFERENCES$`.
+
+- `"messageSecret": "<some uuid>"`
+
+Without this, the bridge will refuse to be installed.
+
+Example:
+
+```json
+{
+  "...": "...",
+  "messageSecret": ""
+}
+```
+
+## Step 2: Enable in remote config 
+
+Using the method of your choice, generate a remote config file that has the bridge feature 
+enabled + some feature & domain combinations. 
+
+
+For example, to enable `aiChat` on `duckduckgo.com` domains - you would place the following override
+in the relevant platform file. This is how the per-domain restrictions are enforced in the JavaScript layer.
+
+```json
+{
+  "features": {
+    "...": "...",
+    "messageBridge": {
+      "state": "enabled",
+      "settings": {
+        "aiChat": "disabled",
+        "domains": [
+          {
+            "domain": "duckduckgo.com",
+            "patchSettings": [
+              {
+                "op": "replace",
+                "path": "/aiChat",
+                "value": "enabled"
+              }
+            ]
+          }
+        ]
+      }
+    }
+  }
+}
+```
+
+**NOTE:** Native platforms should continue to verify the sending domain when any messages are received.  
+
+## Example
+
+In a domain where the bridge is enabled, the following API becomes available to the page.
+
+```javascript
+const bridge = navigator.duckduckgo?.createMessageBridge?.('exampleFeature');
+bridge.notify('pixel');
+```
+
+That `notify` ^ call will result in a {@link "Messaging Schema".NotificationMessage "NotificationMessage"} being sent 
+to the 'native' layer.
+
+```json
+{
+  "context": "contentScopeScriptsIsolated",
+  "featureName": "exampleFeature",
+  "method": "pixel"
+}
+```
+
+Likewise with `Requests` and `Subscriptions` - as far as the 'native' side is concerned, they are handled with the same
+Messaging Schema types.
+
+

typedoc.js

@@ -2,7 +2,11 @@ import { OptionDefaults } from 'typedoc';
 
 /** @type {Partial<import('typedoc').TypeDocOptions>} */
 const config = {
-    projectDocuments: ['special-pages/pages/new-tab/app/new-tab.md'],
+    // prettier-ignore
+    projectDocuments: [
+        'special-pages/pages/new-tab/app/new-tab.md',
+        'injected/docs/*.md',
+    ],
     entryPoints: [
         'injected/entry-points/android.js',
         'injected/entry-points/apple.js',