[Release notes] Add 2.13 release notes (opensearch-project#1810)

* add 2.13 release notes

Signed-off-by: Eric <menwe@amazon.com>

* add version bump

Signed-off-by: Eric <menwe@amazon.com>

* bump version for bwc tests

Signed-off-by: Eric <menwe@amazon.com>

---------

Signed-off-by: Eric <menwe@amazon.com>
(cherry picked from commit 4b43545)

build.gradle

@@ -333,12 +333,8 @@ testClusters.integTest {
     setting 'path.repo', repo.absolutePath
 }
 
-String bwcMinVersion = "1.2.0-SNAPSHOT"
-String bwcBundleVersion = "1.3.2.0"
-Boolean bwcBundleTest = (project.findProperty('customDistributionDownloadType') != null &&
-        project.properties['customDistributionDownloadType'] == "bundle");
-String bwcVersion = bwcBundleTest ? bwcBundleVersion : bwcMinVersion
-String bwcCurrentVersion = opensearch_version.replace("-SNAPSHOT", "")
+String baseVersion = "2.13.0"
+String bwcVersion = baseVersion + ".0"
 String baseName = "obsBwcCluster"
 String bwcFilePath = "src/test/resources/bwc/"
 String remoteFileURL = "https://github.com/opensearch-project/observability/releases/download/1.2.0.0/opensearch-observability-1.2.0.0.zip"

release-notes/opensearch-observability.release-notes-2.13.0.0.md

@@ -0,0 +1,6 @@
+## Version 2.13.0.0 Release Notes
+
+Compatible with OpenSearch 2.13.0
+
+### Maintenance
+Increment version to 2.13.0-SNAPSHOT ([#1796](https://github.com/opensearch-project/observability/pull/1796))