add centos6 installation guide

CentOS6-Compile.md

@@ -0,0 +1,41 @@
+# CentOS6 installation guide
+
+## prepare
+
++ install libuv1
+
+```bash
+wget https://github.com/libuv/libuv/archive/v1.23.2.tar.gz
+tar zxvf v1.23.2.tar.gz
+cd libuv-1.23.2
+sh autogen.sh
+./configure
+make
+make check # maybe ignored
+make install
+```
+
++ repalce all Ofast to O2 in $PROJECT/cmake/flags.cmake
+
++ e.g.
+
+```bash
+sed -i 's/Ofast/O2/g' ./cmake/flags.cmake
+```
+
++ You must install gcc about 5.4+ (I've test 6.4)
+
+## install
+
++ Cmake project using newest gcc with libuv
+
+```bash
+mkdir build
+cd build
+export CC=/usr/local/bin/gcc
+export CXX=/usr/local/bin/g++
+cmake .. -DUV_INCLUDE_DIR=/usr/local/include -DUV_LIBRARY=/usr/local/lib/libuv.a
+make
+```
+
++ It works