Update compatibility matrix to reflect supported versions (#325)

Author: Anaethelion

.doc/installation.asciidoc

@@ -53,34 +53,8 @@ go run main.go
 [discrete]
 === {es} Version Compatibility
 
-The client major versions correspond to the {es} major versions: to connect to 
-{es} `7.x`, use a `7.x` version of the client, to connect to {es} `6.x`, use a 
-`6.x` version of the client, and so on.
+Language clients are forward compatible; meaning that clients support communicating
+with greater minor versions of {es}.
 
-[NOTE]
---
-While the 5.x version of the client is available, it is no longer actively 
-maintained, neither the corresponding {es} version. For more information, refer 
-to https://www.elastic.co/support/eol[Elastic product end of life dates].
---
-
-[%header,cols=2*]
-|===
-|{es} Version
-|Client Version
-
-|`master`
-|`master`
-
-|`7.x`
-|`7.x`
-
-|`6.x`
-|`6.x`
-
-|`5.x`
-|`5.x`
-|===
-
-The `master` branch of the client is compatible with the `master` branch of 
-{es}.
+Elastic language clients are also backwards compatible with lesser supported
+minor {es} versions.

README.md

@@ -12,7 +12,11 @@ The official Go client for [Elasticsearch](https://www.elastic.co/products/elast
 
 ## Compatibility
 
-The client major versions correspond to the compatible Elasticsearch major versions: to connect to Elasticsearch `7.x`, use a [`7.x`](https://github.com/elastic/go-elasticsearch/tree/7.x) version of the client, to connect to Elasticsearch `6.x`, use a [`6.x`](https://github.com/elastic/go-elasticsearch/tree/6.x) version of the client.
+Language clients are forward compatible; meaning that clients support communicating
+with greater minor versions of Elasticsearch.
+
+Elastic language clients are also backwards compatible with lesser supported
+minor Elasticsearch versions.
 
 When using Go modules, include the version in the import path, and specify either an explicit version or a branch: