add reference to packages, instead of writing down solutions for specific os

Author: sakajunquality

README.md

@@ -50,9 +50,7 @@ Prerequisite
 
 - Node.js 4.x or up (test up to 6.7.0)
 - Database (PostgreSQL, MySQL, MariaDB, SQLite, MSSQL) use charset `utf8`
-- npm
-- gcc/make
-	- `sudo yum groupinstall 'Development Tools'` for RHEL, `sudo apt-get install build-essential` for Debian
+- npm (and its dependencies, especially [uWebSockets](https://github.com/uWebSockets/uWebSockets#nodejs-developers), [node-gyp](https://github.com/nodejs/node-gyp#installation))
 
 Get started
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