Make installation script show friendlys message if it is being executed in Mac or any OS

[mekya]

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Short description

Have better OS detection in script, and show clear error if not supported Have Quickstart instructions a) Say Linux only b) point to detailed AMS instructions

$ sudo ./install_ant-media-server.sh
df: --total: No such file or directory
df: -k: No such file or directory
df: -m: No such file or directory
df: --output=avail: No such file or directory
Downloading the latest version of Ant Media Server Community Edition.
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inflating: ant-media-server/README.md
JAVA_HOME : /usr/lib/jvm/java-17-openjdk-amd64/
xargs: invalid option -- i
usage: xargs [-0opt] [-E eofstr] [-I replstr [-R replacements] [-S replsize]]
[-J replstr] [-L number] [-n number [-x]] [-P maxprocs]
[-s size] [utility [argument ...]]
find: /usr/lib/jvm/: No such file or directory
mkdir: /usr/lib/jvm: Operation not permitted
ln: /usr/lib/jvm/java-17-openjdk-amd64//lib/amd64/: No such file or directory