Update opendistro-1.8 branch with 1.0.0/1.8.0 breaking changes support docs (#245)

* Update opendistro-1.8 branch with 1.8.0 breaking changes support docs

* Update opendistro-1.8 branch with 1.0.0 breaking changes support docs

Author: peterzhuamazon

release-notes/opendistro-for-elasticsearch-release-notes-1.0.0.md

@@ -1,5 +1,10 @@
 ## Open Distro for Elasticsearch 1.0.0 Release Notes
 
+## **Breaking Changes**
+
+* Open Distro for Elasticsearch 1.0.0 uses Elasticsearch 7.0.1, which has numerous breaking changes from 6.x.x.
+* Please follow the support docs during the upgrade. ([Support Docs](https://opendistro.github.io/for-elasticsearch-docs/docs/upgrade/1-0-0/))
+
 ### **ALERTING**
 
 * Added support for Elasticsearch 7.0.1 - PR [41](https://github.com/opendistro-for-elasticsearch/alerting/pull/41)

release-notes/opendistro-for-elasticsearch-release-notes-1.8.0.md

@@ -18,7 +18,7 @@ The release includes the following features, enhancements, infrastructure and do
 
 ## Breaking Changes
 
-* Artifact Name of Anomaly Detection Plugin for **_*DEB*_** and **_*RPM*_** distribution is updated from **opendistro-anomaly-detector** to **opendistro-anomaly-detection**. In order to reduce the impact of this change, we recommend removing the old **opendistro-anomaly-detector** plugin first with your package manager, before installing the upgraded **opendistro-anomaly-detection**.
+* Artifact Name of Anomaly Detection Plugin for **_*DEB*_** and **_*RPM*_** distribution is updated from **opendistro-anomaly-detector** to **opendistro-anomaly-detection**. In order to reduce the impact of this change, we recommend removing the old **opendistro-anomaly-detector** plugin first with your package manager, before installing the upgraded **opendistro-anomaly-detection** ([Support Docs](https://opendistro.github.io/for-elasticsearch-docs/docs/upgrade/1-8-0/)).
 
 ## **Features**