Add known issue notice for AWS auth panic (#23552)

* Add known issue

website/content/docs/release-notes/1.15.0.mdx

@@ -16,6 +16,7 @@ description: |-
 Version | Issue
 ------- | -----
 1.15.0+ | [Vault no longer reports rollback metrics by mountpoint](/vault/docs/upgrading/upgrade-to-1.15.x#rollback-metrics)
+1.15.0  | [Panic in AWS auth method during IAM-based login](/vault/docs/upgrading/upgrade-to-1.15.x#panic-in-aws-auth-method-during-iam-based-login)
 
 ## Vault companion updates
 

website/content/docs/upgrading/upgrade-to-1.15.x.mdx

@@ -50,3 +50,5 @@ option.
 @include 'known-issues/transit-managed-keys-panics.mdx'
 
 @include 'known-issues/transit-managed-keys-sign-fails.mdx'
+
+@include 'known-issues/aws-auth-panics.mdx'

website/content/partials/known-issues/aws-auth-panics.mdx

@@ -0,0 +1,18 @@
+### Panic in AWS auth method during IAM-based login
+
+#### Affected versions
+
+- 1.15.0
+
+#### Issue
+
+A panic can occur in the AWS auth method during [IAM-based](/vault/docs/auth/aws#iam-auth-method)
+login when a [client config](/vault/api-docs/auth/aws#configure-client) does not exist.
+
+#### Workaround
+
+The panic can be avoided by writing an empty [client config](/vault/api-docs/auth/aws#configure-client):
+
+```shell-session
+vault write -f auth/aws/config/client
+```