docs: Add resolved issue to release notes (#5260)

* docs: Add resolved issue to release notes

* Update website/content/docs/release-notes/v0_18_0.mdx

Co-authored-by: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>

* docs: Revise gerund for standards

---------

Co-authored-by: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>

website/content/docs/release-notes/v0_18_0.mdx

@@ -168,5 +168,23 @@ description: |-
     </td>
   </tr>
 
+  <tr>
+    <td style={{verticalAlign: 'middle'}}>
+    0.18.0 (Fixed in 0.18.1)
+    </td>
+    <td style={{verticalAlign: 'middle'}}>
+    Users are incorrectly removed from managed groups
+    </td>
+    <td style={{verticalAlign: 'middle'}}>
+    If your organization has over 10,000 managed groups, Boundary may incorrectly remove users from the managed group memberships.
+    <br /><br />
+    In version 0.18.0 and earlier, there was a maximum number of managed groups supported for an auth method. If you had over 10,000 managed groups, Boundary may have incorrectly removed a user from a group during authentication. This issue is fixed in version 0.18.1. There is no longer a maximum number of managed groups.
+    <br /><br />
+    Learn more:&nbsp; <a href="/boundary/docs/concepts/domain-model/managed-groups">Managed groups</a>
+    <br /><br />
+    <a href="/boundary/tutorials/self-managed-deployment/upgrade-version">Upgrade to the latest version of Boundary</a>
+    </td>
+  </tr>
+
   </tbody>
 </table>