Update README to show support for Node.js 8

PR-URL: #97
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gibson Fahnestock <gib@uk.ibm.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

Author: rnchamberlain

README.md

@@ -9,7 +9,7 @@ platform information and resource usage etc. With the report enabled,
 reports can be triggered on unhandled exceptions, fatal errors, signals
 and calls to a JavaScript API.
 
-Supports Node.js v4, v6 and v7 on AIX, Linux, MacOS, SmartOS and Windows.
+Supports Node.js versions 4, 6 and 8 on AIX, Linux, MacOS, SmartOS and Windows.
 
 ## Usage