Added node.js support doc (#1346)

Co-authored-by: István Zoltán Szabó <istvan.szabo@elastic.co>

README.md

@@ -26,9 +26,33 @@ The official Node.js client for Elasticsearch.
 npm install @elastic/elasticsearch
 ```
 
-### Compatibility
+### Node.js support
 
-The minimum supported version of Node.js is `v8`.
+NOTE: The minimum supported version of Node.js is `v8`.
+
+The client versioning follows the Elastc Stack versioning, this means that
+major, minor, and patch releases are done following a precise schedule that
+often does not coincide with the [Node.js release](https://nodejs.org/en/about/releases/) times.
+
+To avoid support insecure and unsupported versions of Node.js, the
+client **will drop the support of EOL versions of Node.js between minor releases**.
+Typically, as soon as a Node.js version goes into EOL, the client will continue
+to support that version for at least another minor release. If you are using the client
+with a version of Node.js that will be unsupported soon, you will see a warning
+in your logs (the client will start logging the warning with two minors in advance).
+
+Unless you are **always** using a supported version of Node.js, 
+we recommend defining the client dependency in your
+`package.json` with the `~` instead of `^`. In this way, you will lock the
+dependency on the minor release and not the major. (for example, `~7.10.0` instead
+of `^7.10.0`).
+
+| Node.js Version | Node.js EOL date | End of support         |
+| --------------- |------------------| ---------------------- |
+| `8.x`           | `December 2019`  | `7.11` (early 2021)    |       
+| `10.x`          | `Apri 2021`      | `7.12` (mid 2021)      |        
+
+### Compatibility
 
 The library is compatible with all Elasticsearch versions since 5.x, and you should use the same major version of the Elasticsearch instance that you are using.
 

docs/installation.asciidoc

@@ -20,17 +20,52 @@ npm install @elastic/elasticsearch@<major>
 To learn more about the supported major versions, please refer to the 
 <<js-compatibility-matrix>>.
 
+[discrete]
+[[nodejs-support]]
+=== Node.js support
+
+NOTE: The minimum supported version of Node.js is `v8`.
+
+The client versioning follows the {stack} versioning, this means that
+major, minor, and patch releases are done following a precise schedule that
+often does not coincide with the https://nodejs.org/en/about/releases/[Node.js release] times.
+
+To avoid support insecure and unsupported versions of Node.js, the
+client *will drop the support of EOL versions of Node.js between minor releases*.
+Typically, as soon as a Node.js version goes into EOL, the client will continue
+to support that version for at least another minor release. If you are using the client
+with a version of Node.js that will be unsupported soon, you will see a warning
+in your logs (the client will start logging the warning with two minors in advance).
+
+Unless you are *always* using a supported version of Node.js, 
+we recommend defining the client dependency in your
+`package.json` with the `~` instead of `^`. In this way, you will lock the
+dependency on the minor release and not the major. (for example, `~7.10.0` instead
+of `^7.10.0`).
+
+[%header,cols=3*]
+|===
+|Node.js Version
+|Node.js EOL date
+|End of support
+
+|`8.x`
+|December 2019
+|`7.11` (early 2021)
+
+|`10.x`
+|April 2021
+|`7.12` (mid 2021)
+|===
+
 [discrete]
 [[js-compatibility-matrix]]
 === Compatibility matrix
 
-The minimum supported version of Node.js is `v8`.
-
 The library is compatible with all {es} versions since 5.x. We recommend you to
 use the same major version of the client as the {es} instance that you are
 using.
 
-
 [%header,cols=2*]
 |===
 |{es} Version