doc: indicate stream impl from node versions (#424)

* doc: indicate stream impl from node versions

* doc: fix typo

Co-Authored-By: Vincent Weevers <mail@vincentweevers.nl>

Co-authored-by: Vincent Weevers <mail@vincentweevers.nl>

README.md

@@ -24,10 +24,7 @@ As of version 2.0.0 **readable-stream** uses semantic versioning.
 
 ## Version 3.x.x
 
-v3.x.x of `readable-stream` supports Node 6, 8, and 10, as well as
-evergreen browsers, IE 11 and latest Safari. The breaking changes
-introduced by v3 are composed by the combined breaking changes in [Node v9](https://nodejs.org/en/blog/release/v9.0.0/)
-and [Node v10](https://nodejs.org/en/blog/release/v10.0.0/), as follows:
+v3.x.x of `readable-stream` is a cut from Node 10. This version supports Node 6, 8, and 10, as well as evergreen browsers, IE 11 and latest Safari. The breaking changes introduced by v3 are composed by the combined breaking changes in [Node v9](https://nodejs.org/en/blog/release/v9.0.0/) and [Node v10](https://nodejs.org/en/blog/release/v10.0.0/), as follows:
 
 1. Error codes: https://github.com/nodejs/node/pull/13310,
    https://github.com/nodejs/node/pull/13291,
@@ -51,9 +48,7 @@ and [Node v10](https://nodejs.org/en/blog/release/v10.0.0/), as follows:
    https://github.com/nodejs/node/pull/17979
 
 ## Version 2.x.x
-
-v2.x.x of `readable-stream` supports all Node.js version from 0.8, as well as
-evergreen browsers and IE 10 & 11.
+v2.x.x of `readable-stream` is a cut of the stream module from Node 8 (there have been no semver-major changes from Node 4 to 8). This version supports all Node.js versions from 0.8, as well as evergreen browsers and IE 10 & 11.
 
 ### Big Thanks