[ML] Adding a known issue for the ML datafeed auth header problem (#92274)

Due to #41185 datafeeds created prior to 7.0 and not updated since
then have unparseable authorization headers in 8.x. In 8.0-8.3 this
could easily be a non-issue, as such datafeeds were likely forgotten
leftovers and never run. Even if it was a problem, only the datafeed
of interest would need updating with any urgency.

Due to #87884 datafeeds with authorization headers older than 7.0
prevent _all_ datafeeds being listed in 8.4 and 8.5. This in turn
breaks the anomaly detection job management section of the ML UI.

The problem is alleviated by #92168 and fixed by #92221, but we
should warn users that the problem exists in 8.4.0-8.5.3 inclusive.

Author: David Roberts

docs/reference/release-notes/8.4.0.asciidoc

@@ -3,6 +3,23 @@
 
 Also see <<breaking-changes-8.4,Breaking changes in 8.4>>.
 
+[[known-issues-8.4.0]]
+[float]
+=== Known issues
+
+// tag::ml-pre-7-datafeeds-known-issue[]
+* {ml-cap} {dfeeds} cannot be listed if any are not modified since version 6.x
++
+If you have a {dfeed} that was created in version 5.x or 6.x and has not
+been updated since 7.0, it is not possible to list {dfeeds} in 
+8.4 and 8.5. This means that {anomaly-jobs} cannot be managed using
+{kib}. This issue is fixed in 8.6.
++
+If you upgrade to 8.4 or 8.5 with such a {dfeed}, you need to
+work around the problem by updating each {dfeed}'s authorization information
+using https://support.elastic.dev/knowledge/view/b5a879db[these steps].
+// end::ml-pre-7-datafeeds-known-issue[]
+
 [[bug-8.4.0]]
 [float]
 === Bug fixes

docs/reference/release-notes/8.4.1.asciidoc

@@ -18,3 +18,5 @@ Machine Learning::
 * When using date range search with format that does not have all date fields (missing month or day)
 an incorrectly parsed date could be used. The workaround is to use date pattern with all date fields (year, month, day)
 (issue: {es-issue}90187[#90187])
+
+include::8.4.0.asciidoc[tag=ml-pre-7-datafeeds-known-issue]

docs/reference/release-notes/8.4.2.asciidoc

@@ -20,6 +20,7 @@ This regression was fixed in version 8.4.3.
 an incorrectly parsed date could be used. The workaround is to use date pattern with all date fields (year, month, day)
 (issue: {es-issue}90187[#90187])
 
+include::8.4.0.asciidoc[tag=ml-pre-7-datafeeds-known-issue]
 
 [[bug-8.4.2]]
 [float]

docs/reference/release-notes/8.4.3.asciidoc

@@ -28,3 +28,5 @@ Ranking::
 * When using date range search with format that does not have all date fields (missing month or day)
 an incorrectly parsed date could be used. The workaround is to use date pattern with all date fields (year, month, day)
 (issue: {es-issue}90187[#90187])
+
+include::8.4.0.asciidoc[tag=ml-pre-7-datafeeds-known-issue]

docs/reference/release-notes/8.5.0.asciidoc

@@ -14,6 +14,8 @@ to restart nodes while in this state. Upgrade to 8.5.1 as soon as possible to
 avoid the risk of this occurring ({es-pull}91456[#91456]). If your cluster is
 affected by this issue, upgrade to 8.5.3 to repair it ({es-pull}91887[#91887]).
 
+include::8.4.0.asciidoc[tag=ml-pre-7-datafeeds-known-issue]
+
 [[breaking-8.5.0]]
 [float]
 === Breaking changes

docs/reference/release-notes/8.5.1.asciidoc

@@ -4,6 +4,12 @@
 
 Also see <<breaking-changes-8.5,Breaking changes in 8.5>>.
 
+[[known-issues-8.5.1]]
+[float]
+=== Known issues
+
+include::8.4.0.asciidoc[tag=ml-pre-7-datafeeds-known-issue]
+
 [[bug-8.5.1]]
 [float]
 === Bug fixes

docs/reference/release-notes/8.5.2.asciidoc

@@ -4,6 +4,12 @@
 
 Also see <<breaking-changes-8.5,Breaking changes in 8.5>>.
 
+[[known-issues-8.5.2]]
+[float]
+=== Known issues
+
+include::8.4.0.asciidoc[tag=ml-pre-7-datafeeds-known-issue]
+
 [[bug-8.5.2]]
 [float]
 === Bug fixes

docs/reference/release-notes/8.5.3.asciidoc

@@ -3,6 +3,12 @@
 
 Also see <<breaking-changes-8.5,Breaking changes in 8.5>>.
 
+[[known-issues-8.5.3]]
+[float]
+=== Known issues
+
+include::8.4.0.asciidoc[tag=ml-pre-7-datafeeds-known-issue]
+
 [[bug-8.5.3]]
 [float]
 === Bug fixes