Docs: updates Grafana installation for Red Hat, Fedora, RHEL, SUSE, and OpenSUSE (#65232)

* removes references to CentOS

* starts reorg

* complete restructure

* updates alias

* Update docs/sources/setup-grafana/installation/rpm/index.md

* Apply suggestions from code review

Co-authored-by: Dan Cech <dcech@grafana.com>

* incorporates review feedback

* adds install on suse/opensuse

* updates aliases

* Apply suggestions from code review

Co-authored-by: Dan Cech <dcech@grafana.com>

* removes start server content from both topics; adds link to start server docs in Next steps

* Apply suggestions from code review

Co-authored-by: Dan Cech <dcech@grafana.com>

* incorporates review feedback

* Apply suggestions from code review

* typo fix

---------

Co-authored-by: Dan Cech <dcech@grafana.com>

docs/sources/setup-grafana/installation/_index.md

@@ -5,6 +5,7 @@ aliases:
   - ../installation/installation/
   - ../installation/requirements/
   - /docs/grafana/v2.1/installation/install/
+  - ./rpm/
 description: Installation guide for Grafana
 title: Install Grafana
 weight: 100
@@ -22,8 +23,9 @@ Grafana relies on other open source software to operate. For a list of open sour
 
 Grafana supports the following operating systems:
 
-- [Debian / Ubuntu]({{< relref "debian/" >}})
-- [RPM-based Linux (Fedora, SUSE/OpenSUSE, RedHat)]({{< relref "rpm/" >}})
+- [Debian/Ubuntu]({{< relref "debian/" >}})
+- [Red Hat/RHEL/Fedora]({{< relref "redhat-rhel-fedora/" >}})
+- [SUSE/OpenSUSE]({{< relref "suse-opensuse/" >}})
 - [macOS]({{< relref "mac/" >}})
 - [Windows]({{< relref "windows/" >}})