Update docs about EQL CCS (#91542)

docs/reference/eql/eql-search-api.asciidoc

@@ -48,7 +48,7 @@ or alias.
 * See <<eql-required-fields>>.
 
 * experimental:[] For cross-cluster search, the local and remote clusters must
-use the same {es} version. For security, see <<remote-clusters-security>>.
+use the same {es} version if they have versions prior to 7.17.7 (included) or prior to 8.5.1 (included). For security, see <<remote-clusters-security>>.
 
 [[eql-search-api-limitations]]
 ===== Limitations

docs/reference/eql/eql.asciidoc

@@ -797,9 +797,10 @@ You can also manually delete saved synchronous searches using the
 
 experimental::[]
 
-The EQL search API supports <<modules-cross-cluster-search,cross-cluster
-search>>. However, the local and <<remote-clusters,remote clusters>>
-must use the same {es} version.
+The EQL search API supports <<modules-cross-cluster-search,cross-cluster search>>.
+However, the local and <<remote-clusters,remote clusters>>
+must use the same {es} version
+if they have versions prior to 7.17.7 (included) or prior to 8.5.1 (included).
 
 The following <<cluster-update-settings,cluster update settings>> request
 adds two remote clusters: `cluster_one` and `cluster_two`.

docs/reference/migration/migrate_8_0/rest-api-changes.asciidoc

@@ -197,7 +197,7 @@ remote 8.x cluster.
 include::{es-repo-dir}/search/search-your-data/ccs-version-compat-matrix.asciidoc[]
 
 IMPORTANT: For the {ref}/eql-search-api.html[EQL search API], the local and
-remote clusters must use the same {es} version.
+remote clusters must use the same {es} version if they have versions prior to 7.17.7 (included) or prior to 8.5.1 (included).
 
 For example, a local 8.0 cluster can search a remote 7.17 or any remote 8.x
 cluster. However, a search from a local 8.0 cluster to a remote 7.16 or 6.8

docs/reference/search/search-your-data/search-across-clusters.asciidoc

@@ -446,7 +446,7 @@ remote 8.x cluster.
 include::{es-repo-dir}/search/search-your-data/ccs-version-compat-matrix.asciidoc[]
 
 IMPORTANT: For the <<eql-search-api,EQL search API>>, the local and remote
-clusters must use the same {es} version.
+clusters must use the same {es} version if they have versions prior to 7.17.7 (included) or prior to 8.5.1 (included).
 
 For example, a local 8.0 cluster can search a remote 7.17 or any remote 8.x
 cluster. However, a search from a local 8.0 cluster to a remote 7.16 or 6.8