Update note about Node.js support

Node 6 is unofficially supported but not tested on

[ci skip]

Author: Nick Frasser

CHANGELOG.md

@@ -3,7 +3,7 @@
 ### v2.1.8
 
 * Allow mentions with inner @ sign for federated mentions - thanks @juliushaertl!
-* Drop official Internet Explorer 8 support (still supported unofficially but may break in future releases)
+* Drop official support for Internet Explorer 8 and Node.js 6 (still supported unofficially but may break in future releases)
 * Update dev dependencies
 
 ### v2.1.7

README.md

@@ -195,7 +195,7 @@ You can use either [es5-shim](https://github.com/es-shims/es5-shim) (sham also r
 
 ## Node.js Support
 
-Linkify is tested on Node.js 6 and up. Older versions are unofficially supported.
+Linkify is tested on Node.js 8 and up. Older versions are unofficially supported.
 
 ## Downloads