docs: add usage notice for CLI analytics (#29382)

This is going to be linked to users who want to know more about
analytics.

PR Close #29382

aio/content/marketing/analytics.md

@@ -0,0 +1,66 @@
+# Usage Metrics Gathering
+You can help the Angular Team to prioritize features and improvements by permitting the Angular
+team to send command-line command usage statistics to Google. The Angular Team does not collect
+usage statistics unless you explicitly opt in during the Angular CLI installation or upgrade.
+
+## What is collected?
+Usage analytics include the commands and selected flags for each execution. Usage analytics may
+include the following information:
+
+- Your operating system (Mac, Linux distribution, Windows) and its version.
+- Number of CPUs, amount of RAM.
+- Node and Angular CLI version (local version only).
+- How long each command took to initialize and execute.
+- Command name that was run.
+- For Schematics commands (add, generate, new and update), a list of whitelisted flags.
+- For build commands (build, serve), the number and size of bundles (initial and lazy),
+  compilation units, the time it took to build and rebuild, and basic Angular-specific
+  API usage. *This data is collected only if usage analytics gathering is enabled for
+  the project.*
+- Error code of exceptions and crash data. No stack trace is collected.
+
+Only Angular owned and developed schematics and builders are reported. Third-party schematics and
+builders do not send data to the Angular Team.
+
+## Opting in
+When installing the Angular CLI or upgrading an existing version, you are prompted to allow global
+collection of usage statistics. If you say no or skip the prompt, no data is collected.
+
+The first time a command affecting the project is run, you are prompted to allow collection of data
+related to the project. If you say no or skip the prompt, no data is collected for that project.
+
+Starting with version 8, we added the `analytics` command to the CLI. You can change your opt-in
+decision at any time using this command.
+
+### Disabling usage analytics
+To disable analytics gathering, run the following command:
+
+```bash
+# Disable all usage analytics.
+ng analytics off
+
+# Disable project-specific usage analytics.
+ng analytics project off
+```
+
+### Enabling usage analytics
+To enable usage analytics, run the following command:
+
+```bash
+# Enable all usage analytics.
+ng analytics on
+
+# Enable project-specific usage analytics.
+ng analytics project on
+```
+
+### Prompting
+To prompt the user again about usage analytics, run the following command:
+
+```bash
+# Prompt for all usage analytics.
+ng analytics prompt
+
+# Prompt for project-specific usage analytics.
+ng analytics project prompt
+```

aio/content/navigation.json

@@ -688,6 +688,11 @@
           "url": "https://blog.angular.io/",
           "title": "Blog",
           "tooltip": "Angular Blog"
+        },
+        {
+          "url": "analytics",
+          "title": "Usage Analytics",
+          "tooltip": "Angular Usage Analytics"
         }
       ]
     },