Backport of Add known issue notice for #18636. into release/1.16.x (#18653)

backport of commit a2a903fb81

Co-authored-by: Derek Menteer <derek.menteer@hashicorp.com>

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## 1.16.1 (August 8, 2023)
 
+KNOWN ISSUES:
+
+* connect: Consul versions 1.16.0 and 1.16.1 may have issues when a snapshot restore is performed and the servers are hosting xDS streams. When this bug triggers, it will cause Envoy to incorrectly populate upstream endpoints. This bug only impacts agent-less service mesh and should be fixed in Consul 1.16.2 by [GH-18636](https://github.com/hashicorp/consul/pull/18636).
+
 SECURITY:
 
 * Update `golang.org/x/net` to v0.13.0 to address [CVE-2023-3978](https://nvd.nist.gov/vuln/detail/CVE-2023-3978). [[GH-18358](https://github.com/hashicorp/consul/issues/18358)]
@@ -59,6 +63,10 @@ https://github.com/rboyer/safeio/pull/3 [[GH-18302](https://github.com/hashicorp
 
 ## 1.16.0 (June 26, 2023)
 
+KNOWN ISSUES:
+
+* connect: Consul versions 1.16.0 and 1.16.1 may have issues when a snapshot restore is performed and the servers are hosting xDS streams. When this bug triggers, it will cause Envoy to incorrectly populate upstream endpoints. This bug only impacts agent-less service mesh and should be fixed in Consul 1.16.2 by [GH-18636](https://github.com/hashicorp/consul/pull/18636).
+
 BREAKING CHANGES:
 
 * api: The `/v1/health/connect/` and `/v1/health/ingress/` endpoints now immediately return 403 "Permission Denied" errors whenever a token with insufficient `service:read` permissions is provided. Prior to this change, the endpoints returned a success code with an empty result list when a token with insufficient permissions was provided. [[GH-17424](https://github.com/hashicorp/consul/issues/17424)]

website/content/docs/release-notes/consul/v1_16_x.mdx

@@ -64,6 +64,16 @@ We are pleased to announce the following Consul updates.
 
 For more detailed information, please refer to the [upgrade details page](/consul/docs/upgrading/upgrade-specific) and the changelogs.
 
+## Known Issues
+
+The following issues are known to exist in the v1.16.x releases:
+
+- v1.16.0 - v1.16.1 may have issues when a snapshot restore is performed
+    and the servers are hosting xDS streams. When this bug triggers, it
+    will cause Envoy to incorrectly populate upstream endpoints. It is
+    currently not recommended for service mesh users running agent-less
+    workloads to upgrade Consul to these versions.
+
 ## Changelogs
 
 The changelogs for this major release version and any maintenance versions are listed below.

website/content/docs/upgrading/upgrade-specific.mdx

@@ -16,6 +16,12 @@ upgrade flow.
 
 ## Consul 1.16.x
 
+#### Known issues
+
+Service mesh in Consul versions 1.16.0 and 1.16.1 may have issues when a snapshot restore is performed and the servers are hosting xDS streams.
+When this bug triggers, it will cause Envoy to incorrectly populate upstream endpoints. Due to this issue, it is currently not recommended for
+service mesh users running agent-less workloads to upgrade Consul to these versions.
+
 #### API health endpoints return different status code
 
 Consul versions 1.16.0+ now return an error 403 "Permission denied" status