Fold creating-a-browser-check into the browser check quickstart

Merge the welcome screenshot and setup bullets into the quickstart's first
step, remove the orphaned page, and redirect its old URLs.

Author: stefanjudis

detect/synthetic-monitoring/browser-checks/quickstart.mdx

@@ -23,10 +23,23 @@ Browser Checks are perfect for monitoring realistic user flows within your appli
 
 <Steps>
   <Step title="Create a Browser Check">
-
+    <Frame>
+      <img
+        className="block dark:hidden"
+        src="/images/next/quickstart-welcome-light.png"
+        alt="Light mode interface"
+      />
+      <img
+        className="hidden dark:block"
+        src="/images/next/quickstart-welcome-dark.png"
+        alt="Dark mode interface"
+      />
+    </Frame>
 
   -  **Head to [Create a Check](https://app.checklyhq.com/accounts/create)**
   -  **Choose "Browser Check"** for comprehensive website monitoring
+  -  **Enter your website URL** (e.g., `https://your-website.com`)
+  -  **Click "Create Check"**
   </Step>
 
 <Step title="Edit Your Test Script">

docs.json

@@ -1359,6 +1359,14 @@
       "source": "/quickstarts/playwright-check",
       "destination": "/detect/synthetic-monitoring/playwright-checks/quickstart"
     },
+    {
+      "source": "/quickstarts/creating-a-browser-check",
+      "destination": "/detect/synthetic-monitoring/browser-checks/quickstart"
+    },
+    {
+      "source": "/detect/synthetic-monitoring/browser-checks/creating-a-browser-check",
+      "destination": "/detect/synthetic-monitoring/browser-checks/quickstart"
+    },
     {
       "source": "/ai/rules",
       "destination": "/ai/overview"