docs: update README ToC links and fix typos

- Update 3.1 and 3.2 links from CentOS to Enterprise Linux filenames
- Correct labels: "CentOS 7" → "Enterprise Linux (RHEL/Rocky/AlmaLinux)"
- Fix "Reports Admistrative" → "Reports Administrative"
- Fix "requriments" (×2) → "requirements"

Author: somethingwithproof

README.md

@@ -109,9 +109,9 @@ PARTICULAR PURPOSE. See the GNU General Public License for more details.
 
 3. Installing Cacti on Linux
 
-   3.1. [Installation Under CentOS 7 - LAMP Stack](Install-Under-CentOS_LAMP.md)
+   3.1. [Installation Under Enterprise Linux (RHEL/Rocky/AlmaLinux) - LAMP Stack](Install-Under-Enterprise-Linux-LAMP.md)
 
-   3.2. [Installation Under CentOS 7 - LEMP Stack](Install-Under-CentOS_LEMP.md)
+   3.2. [Installation Under Enterprise Linux (RHEL/Rocky/AlmaLinux) - LEMP Stack](Install-Under-Enterprise-Linux-LEMP.md)
 
    3.3.
    [Installation Under Ubuntu/Debian - LAMP Stack](Installing-Under-Ubuntu-Debian.md)
@@ -264,7 +264,7 @@ PARTICULAR PURPOSE. See the GNU General Public License for more details.
 
 13. Reporting
 
-    13.1. [Reports Admistrative Interface](Reports-Admin.md)
+    13.1. [Reports Administrative Interface](Reports-Admin.md)
 
     13.2. [Reports User Interface](Reports-User.md)