Add emoji to the code review page

Adds the red circle, yellow diamond, and blue circle emoji to the
code review page for extra visual cues.

doc/development/code_review.md

@@ -75,11 +75,11 @@ page, with these behaviors:
 1. [Trainee maintainers](https://about.gitlab.com/handbook/engineering/workflow/code-review/#trainee-maintainer)
    are three times as likely to be picked as other reviewers.
 1. Team members whose Slack or [GitLab status](../user/profile/index.md#current-status) emoji
-   is `:large_blue_circle:` are more likely to be picked. This applies to both reviewers and trainee maintainers.
+   is 🔵 `:large_blue_circle:` are more likely to be picked. This applies to both reviewers and trainee maintainers.
    - Reviewers with `:large_blue_circle:` are two times as likely to be picked as other reviewers.
    - Trainee maintainers with `:large_blue_circle:` are four times as likely to be picked as other reviewers.
 1. People whose [GitLab status](../user/profile/index.md#current-status) emoji
-   is `:large_orange_diamond:` are half as likely to be picked. This applies to both reviewers and trainee maintainers.
+   is 🔶 `:large_orange_diamond:` are half as likely to be picked. This applies to both reviewers and trainee maintainers.
 1. It always picks the same reviewers and maintainers for the same
    branch name (unless their OOO status changes, as in point 1). It
    removes leading `ce-` and `ee-`, and trailing `-ce` and `-ee`, so
@@ -508,7 +508,7 @@ and get on with their work quickly.
 
 If you think you are at capacity and are unable to accept any more reviews until
 some have been completed, communicate this through your GitLab status by setting
-the `:red_circle:` emoji and mentioning that you are at capacity in the status
+the 🔴 `:red_circle:` emoji and mentioning that you are at capacity in the status
 text. This guides contributors to pick a different reviewer, helping us to
 meet the SLO.