Update supported node.js version

Support includes v9.x, but no v10.x

Signed-off-by: Xaver Maierhofer <xaver.maierhofer@xwissen.info>

Author: xf-

README.md

@@ -68,7 +68,7 @@ Just to more confusion: We are still friends with HackMD :heart:
 
 ### Prerequisite
 
-- Node.js 6.x or up (test up to 7.5.0)
+- Node.js 6.x or up (test up to 7.5.0) and <10.x
 - Database (PostgreSQL, MySQL, MariaDB, SQLite, MSSQL) use charset `utf8`
 - npm (and its dependencies, especially [uWebSockets](https://github.com/uWebSockets/uWebSockets#nodejs-developers), [node-gyp](https://github.com/nodejs/node-gyp#installation))
 - For **building** CodiMD we recommend to use a machine with at least **2GB** RAM