lmpIdSystem: Add initial documentation

dev-docs/modules/userid-submodules/lmpid.md

@@ -0,0 +1,32 @@
+---
+layout: userid
+title: LMPID
+description: LMPID User ID sub-module
+useridmodule: lmpIdSystem
+---
+
+The Loblaw Media Private ID (LMPID) is the Loblaw Advance identity solution deployed by its media partners. LMPID leverages encrypted user registration information to provide a privacy-conscious, secure, and reliable identifier to power Loblaw Advance's digital advertising ecosystem.
+
+## LMPID Registration
+
+If you're a media company looking to partner with Loblaw Advance, please reach out to us through our [Contact page](https://www.loblawadvance.ca/contact-us)
+
+## LMPID Configuration
+
+First, make sure to add the LMPID submodule to your Prebid.js package with:
+
+```bash
+gulp build --modules=lmpIdSystem,userId
+```
+
+The following configuration parameters are available:
+
+```javascript
+pbjs.setConfig({
+  userSync: {
+    userIds: [{
+      name: 'lmpid'
+    }]
+  }
+});
+```