Update 'Contributing to Project: Serenity'

Contributing-to-Project%3A-Serenity.md

@@ -15,6 +15,8 @@ Contributing to Project: Serenity is pretty straightforward. In this guide, ther
 
 `git pull origin main`
 
+*A reminder: After pulling the latest version, you must open ProjectSerenity.sln and rebuild using **Build** -> **Build Solution** (or Ctrl+Shift+B).*
+
 ### 2. Create a New Branch
 
 Always create a new branch for your task or feature. **Never commit directly to main.**
@@ -83,6 +85,9 @@ We review all changes before they're merged into the main branch. This is to ens
 2. Select the **main** branch
 3. Click **Pull**
 
+
+*A reminder: After pulling the latest version, you must open ProjectSerenity.sln and rebuild using **Build** -> **Build Solution** (or Ctrl+Shift+B).*
+
 ### 2. Create a New Branch
 
 1. Click **Branch**