doc: update the CentOS, RHEL and Rocky Linux installation instructions

I've split the previously singular "CentOS/RHEL/Rocky" section into 3
sections. They each benefit from having their own steps.

I've also copied steps from [EPEL Getting Started] documentation,
including steps that don't seem to be required because it seems to be
best practice (although I do not understand it). Notably, this is not
required for CentOS Stream:

```
dnf config-manager --set-enabled crb
```

And this is not required for Red Hat:

```
subscription-manager repos --enable codeready-builder-for-rhel-10-$(arch)-rpms
```

And neither are available on Rocky Linux 10. Hence, all 3 have slightly
different instructions.

It has been suggested (see [here][suggest1] and [here][suggest2]) that
the installation instructions should just link to the [EPEL Getting
Started] documentation and just contain this step:

```
sudo dnf install ripgrep
```

However, this is not sufficient to actually install ripgrep from a
base installation of these Linux distributions. I tested this via the
`dokken/centos-stream-10:sha-d1e294f`, `rockylinux/rockylinux:10` and
`redhat/ubi10` Docker images on DockerHub.

While this does mean ripgrep's installation instructions can become out
of sync from upstream, this is *always* a risk regardless of platform.
The instructions are provided on a best effort basis and generally
should work on the latest release of said platform. If the instructions
result in unhelpful errors (like `dnf install ripgrep` does if you
don't enable EPEL), then that isn't being maximally helpful to users.
I'd rather attempt to give the entire set of instructions and risk
being out of sync.

Also, since the installation instructions include URLs with version
numbers in them, I made the section names include version numbers as
well.

Note: I found using the `dokken/centos-stream-10:sha-d1e294f` Docker
image to be somewhat odd, as I could not find any official CentOS
Docker images. [This][DockerHub-CentOS] is still the first hit on
Google, but all of its tags have been deleted and the image is
deprecated. I was profoundly confused by this given that the [EPEL
Getting Started] documentation *specifically* cites CentOS 10. In fact,
it is citing CentOS *Stream* 10, which is something wholly distinct
from CentOS. What an absolute **clusterfuck**. If I had just read this
paragraph on Wikipedia from the beginning, I would have saved myself a
lot of confusion:

> In December 2020, Red Hat unilaterally terminated CentOS development in favor
> of CentOS Stream 9, a distribution positioned upstream of RHEL. In March
> 2021, CloudLinux (makers of CloudLinux OS) released a RHEL derivative called
> AlmaLinux. Later in May 2021, one of the CentOS founders (Gregory Kurtzer)
> created the competing Rocky Linux project as a successor to the original
> mission of CentOS.

Ref #2981, Ref #2924

[EPEL Getting Started]: https://docs.fedoraproject.org/en-US/epel/getting-started/
[suggest1]: https://github.com/BurntSushi/ripgrep/pull/2981#issuecomment-3204114293
[suggest2]: https://github.com/BurntSushi/ripgrep/issues/2924#issuecomment-3326357254
[DockerHub-CentOS]: https://hub.docker.com/_/centos

README.md

@@ -302,15 +302,30 @@ and **openSUSE Leap** since 15.1.
 $ sudo zypper install ripgrep
 ```
 
-If you're a **RHEL/CentOS/Rocky Linux 9** user, you can install ripgrep from
+If you're a **CentOS Stream 10** user, you can install ripgrep from the
-the [EPEL](https://docs.fedoraproject.org/en-US/epel/) repository:
+[EPEL](https://docs.fedoraproject.org/en-US/epel/getting-started/) repository:
 
 ```
 $ sudo dnf config-manager --set-enabled crb
-$ sudo dnf install -y \
+$ sudo dnf install https://dl.fedoraproject.org/pub/epel/epel-release-latest-10.noarch.rpm
-    https://dl.fedoraproject.org/pub/epel/epel-release-latest-9.noarch.rpm \
+$ sudo dnf install ripgrep
-    https://dl.fedoraproject.org/pub/epel/epel-next-release-latest-9.noarch.rpm
+```
-$ sudo dnf install -y ripgrep
+
+If you're a **Red Hat 10** user, you can install ripgrep from the
+[EPEL](https://docs.fedoraproject.org/en-US/epel/getting-started/) repository:
+
+```
+$ sudo subscription-manager repos --enable codeready-builder-for-rhel-10-$(arch)-rpms
+$ sudo dnf install https://dl.fedoraproject.org/pub/epel/epel-release-latest-10.noarch.rpm
+$ sudo dnf install ripgrep
+```
+
+If you're a **Rocky Linux 10** user, you can install ripgrep from the
+[EPEL](https://docs.fedoraproject.org/en-US/epel/getting-started/) repository:
+
+```
+$ sudo dnf install https://dl.fedoraproject.org/pub/epel/epel-release-latest-10.noarch.rpm
+$ sudo dnf install ripgrep
 ```
 
 If you're a **Nix** user, you can install ripgrep from