update environment variable in mac code example

Example 1: update path variable mac

export PATH=$PATH:/new/dir/location1
export PATH=$PATH:/new/dir1:/dir2:/dir/path/no3

Example 2: mac set environment variable

HIMANSHUs-MacBook-Pro:~ himanshu$ export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_131.jdk/Contents/Home