Fix Linux distribution titles

Author: petk

_posts/01-06-01-Linux-Setup.md

@@ -7,12 +7,10 @@ anchor:  linux_setup
 
 Most GNU/Linux distributions come with PHP available from the official repositories, but those packages usually are a little behind the current stable version. There are multiple ways to get newer PHP versions on such distributions.
 
-## Debian-based distributions
+### Ubuntu-based distributions
 
 On Ubuntu and Debian-based GNU/Linux distributions, for instance, the best alternatives for native packages are provided and maintened by [Ondřej Surý][Ondrej Sury Blog], through his Personal Package Archive (PPA) on Ubuntu and DPA/bikeshed on Debian. Find instructions for each of these below.
 
-### Ubuntu-based distributions
-
 For Ubuntu distributions, the [PPA by Ondřej Surý][Ondrej Sury PPA] provides supported PHP versions along with many PECL extensions. To add this PPA to your system, perform the following steps in your terminal:
 
 1. First, add the PPA to your system's software sources using the command:
@@ -29,7 +27,7 @@ For Ubuntu distributions, the [PPA by Ondřej Surý][Ondrej Sury PPA] provides s
 
 This will ensure that your system can access and install the latest PHP packages available in the PPA.
 
-### Debian and other Debian-based distributions
+### Debian-based distributions
 
 For Debian-based distributions, Ondřej Surý also provides a [bikeshed][bikeshed] (Debian equivalent of a PPA). To add the bikeshed to your system and update it, follow these steps:
 
@@ -67,7 +65,7 @@ For Debian-based distributions, Ondřej Surý also provides a [bikeshed][bikeshe
 
 With these steps, your system will be able to install the latest PHP packages from the bikeshed.
 
-## RPM-based distributions
+### RPM-based distributions
 
 On RPM-based distributions (CentOS, Fedora, RHEL, etc.) you can use the [Remi's RPM repository][remi-repo] to install the latest PHP version or to have multiple PHP versions simultaneously available.