chore(perf-issues): Add a mention that thresholds can be configured in settings (#13741)

<!-- Use this checklist to make sure your PR is ready for merge. You may
delete any sections you don't need. -->

## DESCRIBE YOUR PR
*Tell us what you're changing and why. If your PR **resolves an issue**,
please link it so it closes automatically.*

## IS YOUR CHANGE URGENT?  

Help us prioritize incoming PRs by letting us know when the change needs
to go live.
- [ ] Urgent deadline (GA date, etc.): <!-- ENTER DATE HERE -->
- [ ] Other deadline: <!-- ENTER DATE HERE -->
- [x] None: Not urgent, can wait up to 1 week+

## SLA

- Teamwork makes the dream work, so please add a reviewer to your PRs.
- Please give the docs team up to 1 week to review your PR unless you've
added an urgent due date to it.
Thanks in advance for your help!

## PRE-MERGE CHECKLIST

*Make sure you've checked the following before merging your changes:*

- [ ] Checked Vercel preview for correctness, including links
- [ ] PR was reviewed and approved by any necessary SMEs (subject matter
experts)
- [ ] PR was reviewed and approved by a member of the [Sentry docs
team](https://github.com/orgs/getsentry/teams/docs)

Author: leeandher

docs/product/issues/issue-details/performance-issues/img/performance-issue-configuration.png

@@ -30,7 +30,13 @@ Span evidence is information that explains the performance problem in the contex
 
 The "Event Grouping Information" section provides details of how Sentry fingerprinted the event into the group. You can see which parts of the span evidence contributed to the fingerprint.
 
-## Performance Issue Types
+## Configuration
+
+As a Project Admin, you can also manage individual settings for each performance issue detector in **Project Settings > Performance**. Here, you can raise or lower the thresholds for what Sentry considers a performance issue for each project, or disable detection altogether.
+
+![Performance issue configuration](./img/performance-issue-configuration.png)
+
+## Issue Types
 
 The following is a list of available performance issues:
 
@@ -136,11 +142,9 @@ The following is a list of available performance issues:
   </tbody>
 </table>
 
-## Performance Issue Limitations
+## Limitations
 
 Performance issues currently have the following limitations:
 
-- Performance issues can't be merged or deleted
+- Performance issues cannot be merged
 - Custom fingerprinting and grouping can't be applied to performance issues
-
-We're working on removing some or all of these limitations.