Docs: maturity matrix

docs/index.mdx

@@ -151,6 +151,18 @@ This matrix will be updated as Bref and AWS services evolve over time.
             <span className="maturity-icon shadow bg-green-400"></span>
         </td>
     </tr>
+    <tr className="border-b border-gray-200">
+        <td className="p-4 bg-gray-100 font-bold">Real-time applications</td>
+        <td className="p-4 text-center">
+            <span className="maturity-icon shadow bg-green-400"></span>
+        </td>
+        <td className="p-4 text-center">
+            <span className="maturity-icon shadow bg-red-400"></span>
+        </td>
+        <td className="p-4 text-center">
+            <span className="maturity-icon shadow bg-green-400"></span>
+        </td>
+    </tr>
     <tr className="text-xs text-center text-gray-600">
         <td></td>
         <td className="p-3">
@@ -197,6 +209,10 @@ This matrix will be updated as Bref and AWS services evolve over time.
 
     Not impossible, but definitely not the easiest place to start. As a first step, you can follow the guidelines of [The Twelve-Factor App](https://12factor.net). Note that if your application already runs redundantly on multiple servers, it is much more ready for AWS Lambda and the migration could be simple.
 
+- **Real-time applications**
+
+    Warm Lambda invocations are very fast (can be as low as 1ms), but cold starts can take 230ms or more. Cold starts are rare on most applications (less than 0.5% of invocations) and can be further mitigated with [provisioned concurrency](https://docs.aws.amazon.com/lambda/latest/dg/provisioned-concurrency.html), but it's unlikely to ensure they will _never_ happen. This makes Lambda a poor choice for real-time applications where latency must be below 100ms for 100% of requests.
+
 ## Getting started
 
 Get started with Bref by reading the [installation documentation](/docs/setup.mdx).