Usage:
```
$ mkdir RHEL9Doc
$ cd RHEL9Doc
$ fetchdoc.sh https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/9
```
Prerequirement: curl, GNU Parallel
Usage:
```
$ mkdir RHEL9Doc
$ cd RHEL9Doc
$ fetchdoc.sh https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/9
```
Prerequirement: curl, GNU Parallel