Add Product Intelligence review docs

  - Add page for Product Intelligence review
  - Link from Usage Ping guide

doc/development/usage_ping.md

@@ -752,7 +752,7 @@ alt_usage_data(999)
 
 ### Adding counters to build new metrics
 
-When adding the results of two counters, use the `add` usage data method that 
+When adding the results of two counters, use the `add` usage data method that
 handles fallback values and exceptions. It also generates a valid [SQL export](#exporting-usage-ping-sql-queries-and-definitions).
 
 Example usage:
@@ -869,7 +869,7 @@ Ensure you comply with the [Changelog entries guide](changelog.md).
 
 ### 9. Ask for a Product Intelligence Review
 
-On GitLab.com, we have DangerBot setup to monitor Product Intelligence related files and DangerBot recommends a Product Intelligence review. Mention `@gitlab-org/growth/product_intelligence/engineers` in your MR for a review.
+On GitLab.com, we have DangerBot setup to monitor Product Intelligence related files and DangerBot recommends a [Product Intelligence review](usage_ping/product_intelligence_review.md). Mention `@gitlab-org/growth/product_intelligence/engineers` in your MR for a review.
 
 ### 10. Verify your metric
 

doc/development/usage_ping/product_intelligence_review.md

+---
+stage: Growth
+group: Product Intelligence
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
+---
+
+# Product Intelligence review guidelines
+
+This page includes introductory material for a
+[Product Intelligence](https://about.gitlab.com/handbook/engineering/development/growth/product-intelligence/)
+review, and is specific to Product Intelligence reviews. For broader advice and
+general best practices for code reviews, refer to our [code review guide](../code_review.md).
+
+## Resources for Product Intelligence reviewers
+
+- [Usage Ping Guide](../usage_ping.md)
+- [Snowplow Guide](../snowplow.md)
+- [Metrics Dictionary](metrics_dictionary.md)
+
+## Review process
+
+We recommend a Product Intelligence review when an application update touches
+Product Intelligence files.
+
+- Changes that touch `usage_data*` files.
+- Changes to the Metrics Dictionary including files in:
+  - [`config/metrics`](https://gitlab.com/gitlab-org/gitlab/-/tree/master/config/metrics).
+  - [`ee/config/metrics`](https://gitlab.com/gitlab-org/gitlab/-/tree/master/ee/config/metrics).
+  - [`dictionary.md`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/doc/development/usage_ping/dictionary.md).
+  - [`schema.json`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/metrics/schema.json).
+- Changes to `tracking` files.
+- Changes to Product Intelligence tooling. For example,
+  [`Gitlab::UsageMetricDefinitionGenerator`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/generators/gitlab/usage_metric_definition_generator.rb)
+
+### Roles and process
+
+The merge request **author** should:
+
+- Decide whether a Product Intelligence review is needed.
+- If a Product Intelligence review is needed, add the labels
+  `~product intelligence` and `~product intelligence::review pending`.
+- Assign an
+  [engineer](https://gitlab.com/groups/gitlab-org/growth/product-intelligence/engineers/-/group_members?with_inherited_permissions=exclude) from the Product Intelligence team for a review.
+- Set the correct attributes in YAML metrics:
+  - `product_section`, `product_stage`, `product_group`, `product_category`
+  - Provide a clear description of the metric.
+- Update the
+  [Metrics Dictionary](https://gitlab.com/gitlab-org/gitlab/-/blob/master/doc/development/usage_ping/dictionary.md) if it is needed.
+- Add a changelog [according to guidelines](../changelog.md).
+
+The Product Intelligence **reviewer** should:
+
+- Perform a first-pass review on the merge request and suggest improvements to the author.
+- Approve the MR, and relabel the MR with `~"product intelligence::approved"`.
+
+## Review workload distribution
+
+[Danger bot](../dangerbot.md) adds the list of Product Intelligence changed files
+and pings the
+[`@gitlab-org/growth/product-intelligence/engineers`](https://gitlab.com/groups/gitlab-org/growth/product-intelligence/engineers/-/group_members?with_inherited_permissions=exclude) group for merge requests
+that are not drafts.
+
+Any of the Product Intelligence engineers can be assigned for the Product Intelligence review.
+
+### How to review for Product Intelligence
+
+- Check the [metrics location](../usage_ping.md#1-naming-and-placing-the-metrics) in
+  the Usage Ping JSON payload.
+- Add `~database` label and ask for [database review](../database_review.md) for
+  metrics that are based on Database.
+- For tracking using Redis HLL (HyperLogLog):
+  - Check the Redis slot.
+  - Check if a [feature flag is needed](../usage_ping.md#recommendations).
+- Metrics YAML definitions:
+  - Check the metric `description`.
+  - Check the metrics `key_path`.
+  - Check the `product_section`, `product_stage`, `product_group`, `product_category`.
+    Read the [stages file](https://gitlab.com/gitlab-com/www-gitlab-com/blob/master/data/stages.yml).
+  - Check the file location. Consider the time frame, and if the file should be under `ee`.
+  - Check the tiers.