For now, there are 3 packages for the release binaries of Doris: https://doris.apache.org/download
And user may be confused about how to download and deploy these packages.
So I provide a download script for each release, and user can simply download the script and run it, like:
```
> sh download_x64_apache.sh
Begin to download FE from "https://mirrors.tuna.tsinghua.edu.cn/apache/doris/1.2/1.2.3-rc02/apache-doris-fe-1.2.3-bin-x86_64.tar.xz" to "apache-doris-1.2.3-bin/" ...
Total size: 408078012 Bytes
#################################################### 100.0%
Begin to download BE from "https://mirrors.tuna.tsinghua.edu.cn/apache/doris/1.2/1.2.3-rc02/apache-doris-be-1.2.3-bin-x86_64.tar.xz" to "apache-doris-1.2.3-bin/" ...
Total size: 606211324 Bytes
#################################################### 100.0%
Begin to download DEPS from "https://mirrors.tuna.tsinghua.edu.cn/apache/doris/1.2/1.2.3-rc02/apache-doris-dependencies-1.2.3-bin-x86_64.tar.xz" to "apache-doris-1.2.3-bin/" ...
Total size: 253869148 Bytes
#################################################### 100.0%
Begin to assemble the binaries ...
Move java-udf-jar-with-dependencies.jar to be/lib/ ...
Download complete!
You can now deploy Apache Doris from apache-doris-1.2.3-bin/
```
The script will do the rest.
This script will later be published on the Download page of Apache Doris website, so that user can easily get
it and use it.
Currently only for Linux platform. Other platform is untested.
