[8.1] Add release notes for 8.1.1

Co-authored-by: Seth Michael Larson <[email protected]>

Author: github-actions[bot]

docs/guide/release-notes.asciidoc

@@ -1,6 +1,8 @@
 [[release-notes]]
 == Release notes
 
+* <<rn-8-1-1>>
+* <<rn-8-1-0>>
 * <<rn-8-0-0>>
 * <<rn-7-17-1>>
 * <<rn-7-17-0>>
@@ -39,6 +41,31 @@
 * <<rn-7-0-0>>
 
 
+[discrete]
+[[rn-8-1-1]]
+=== 8.1.1 (2022-03-22)
+
+[discrete]
+==== Documents
+
+* Changed the `source` and `dest` parameters of the `reindex` API to be required.
+
+[discrete]
+==== Mappings
+
+* Changed the `fields` parameter of the `field_caps` API to be required.
+
+
+[discrete]
+[[rn-8-1-0]]
+=== 8.1.0 (2022-03-08)
+
+[discrete]
+==== Transforms
+
+* Added the `transform.reset_transform` API
+
+
 [discrete]
 [[rn-8-0-0]]
 === 8.0.0 (2022-02-10)