feat(browser): Experimental features section

src/content/docs/browser/new-relic-browser/browser-pro-features/browser-features.mdx

@@ -21,3 +21,4 @@ Check out our key <InlinePopover type="browser"/> features:
 * <DNT>[Browsers](/docs/browser/new-relic-browser/browser-pro-features/browsers-problem-patterns-type-or-platform/)</DNT>: View webpage data by browser type or platform
 * <DNT>[Distributed tracing](/docs/browser/new-relic-browser/browser-pro-features/browser-data-distributed-tracing/)</DNT>: Connect backend and frontend performance
 * <DNT>[Browser apps index](/docs/browser/new-relic-browser/getting-started/browser-apps-index/)</DNT>: View a list of all your browser apps
+* <DNT>[Marks and measures](/docs/browser/new-relic-browser/browser-pro-features/marks-and-measures/)</DNT>: Automatically track native marks and measures

src/content/docs/browser/new-relic-browser/browser-pro-features/marks-and-measures.mdx

@@ -0,0 +1,47 @@
+---
+title: 'Automatically track native marks and measures'
+tags:
+  - Browser
+  - Browser monitoring
+  - Experimental features
+metaDescription: "Observes and reports on the performance of your webpages by automatically tracking native marks and measures."
+freshnessValidatedDate: never
+---
+
+<Callout variant="important">
+  This is an experimental browser feature and is subject to change. Use this feature with caution. It's available only with the browser agent installed via copy/paste or NPM.
+</Callout>
+
+
+[Marks](https://developer.mozilla.org/en-US/docs/Web/API/Performance/mark) and [measures](https://developer.mozilla.org/en-US/docs/Web/API/Performance/measure) are standard methods to observe and report on the performance of your webpages. They're generic events native to the browser. You can use them to measure the duration of any task. The New Relic browser agent can automatically track marks and measures as store them as `BrowserPerformance` events.
+
+## Enable marks and measures monitoring [#enable-feature]
+
+To enable this feature: 
+
+1. Make sure you're using browser agent 1.272.0 or later. 
+2. Locate the agent code in your webpage HTML or JS application.
+3. In the `init` configuration object, and add the `performance` feature configuration. 
+
+    Here's an example to enable both marks and measures detection:
+    ```js
+    <script type="text/javascript"> ;window.NREUM||(NREUM={});init={ …, performance: {capture_marks: true, capture_measures: true} }:
+    ```
+4. Deploy your app.
+
+## Find your data in New Relic [#find-data]
+
+Once enabled, the agent stores marks and measures data under the `BrowserPerformance` event type in New Relic. To find this data, try the following queries and then create custom dashboards to track performance.
+
+Query 1: This NRQL query retrieves all `BrowserPerformance` events for the specified `appName` ("My Application") where the `entryName` is either `mark` or `measure`. 
+
+    ```nrql
+    FROM BrowserPerformance SELECT * WHERE appName = 'My Application' AND entryName = 'mark' OR entryName = 'measure'
+    ```
+
+Query 2: This NRQL query calculates the average `entryDuration` for mark and measure events within the specified `appName`. The `FACET entryName` clause groups the results by the `entryName` field, providing separate average durations for mark and measure events. This can be useful for comparing the average performance of marks versus measures. 
+
+    ```nrql
+    FROM BrowserPerformance SELECT average(entryDuration) WHERE appName = 'My Application' AND entryName = 'mark' OR entryName = 'measure' FACET entryName
+    ```
+

src/content/docs/browser/new-relic-browser/configuration/experimental-features.mdx

@@ -0,0 +1,13 @@
+---
+title: 'Experimental features in browser monitoring'
+metaDescription: "Opt-in to use experimental features in New Relic browser monitoring before they're generally available."
+freshnessValidatedDate: never
+---
+
+New Relic browser agent offers a range of features to enhance your application monitoring capabilities. Some features are released in experimental state to ensure stability and reliability. These features may change or may lack support. You must use them with caution.
+
+
+## Current experimental features
+
+The following experimental features are available:
+* Browser agent v1.272.0: [Automatically track native marks and measures as `BrowserPerformance` events](/docs/browser/new-relic-browser/browser-pro-features/marks-and-measures)

src/nav/browser.yml

@@ -54,6 +54,8 @@ pages:
     pages:
       - title: Browser monitoring features
         path: /docs/browser/new-relic-browser/browser-pro-features/browser-features
+      - title: Experimental features
+        path: /docs/browser/new-relic-browser/configuration/experimental-features
       - title: Summary page
         path: /docs/browser/browser-monitoring/getting-started/browser-summary-page
       - title: Session replay
@@ -78,6 +80,8 @@ pages:
         path: /docs/browser/new-relic-browser/browser-pro-features/browser-data-distributed-tracing
       - title: User actions
         path: /docs/browser/browser-monitoring/browser-pro-features/user-actions
+      - title: Marks and measures
+      path: /docs/browser/new-relic-browser/browser-pro-features/marks-and-measures
   - title: Monitor single page applications (SPA)
     pages:
       - title: Introduction to SPA monitoring