Add 8.4.0-alpha.1 to changelog

Author: Anaethelion

CHANGELOG.md

@@ -1,3 +1,50 @@
+# 8.4.0-alpha.1
+
+This prerelease introduces a new typed API generated from the [elasticsearch-specification](https://github.com/elastic/elasticsearch-specification). This generation from the common specification allows us to provide a complete API which uses an exhaustive hierarchy of types  reflecting the possibilities given by Elasticsearch. 
+
+This new API is the next iteration of the Go client for Elasticsearch, it now lives alongside the existing API, it is in `alpha` state and will gain features over time and releases.
+
+## What's new
+
+The `TypedClient` is built around a fluent builder for easier request creation and a collection of structures and helpers that mimics as closely as possible the Elasticsearch JSON API.
+
+As a first example, here is a search request:
+```go
+cfg := elasticsearch.Config{
+	// Define your configuration
+}
+es, _ := elasticsearch.NewTypedClient(cfg)
+res, err := es.Search().
+    Index("index_name").
+    Request(&search.Request{
+        Query: &types.QueryContainer{
+            Match: map[types.Field]types.MatchQuery{
+                "name": {Query: "Foo"},
+            },
+        },
+    },
+    ).Do(context.Background())
+```
+
+The `Request` uses the structures found in the `typedapi/types` package which will lead you along the possibilities. A builder for each structure that allows easier access and declaration is also provided.
+
+More on the specifics and a few examples of standard use-cases can be found in the [TypedAPI section of the documentation](https://www.elastic.co/guide/en/elasticsearch/client/go-api/master/typedapi.html).
+
+## Limitations
+
+While most of the endpoints are covered, a few points are still being worked on and will be part of future releases:
+
+* NDJSON endpoints: `bulk`, `msearch`, `msearch_template`, `ML.post_data`, `find_structure`, to name a few.
+* Response and Errors structures with deserialization.
+
+## Transport & config
+
+While being different, the new API uses all the existing layers that were built so far, `elastic-transport-go` remains the preferred transport and all your configuration and credentials applies, same as before.
+
+## Feedback
+
+Feedback is very welcome, play with it, use it, let us know what you think!
+
 # 8.3.0
 
 ## API