Introduce `include` folder for common sections

Start with B9S install from SafeB9SInstaller as an example

_config.yml

@@ -185,6 +185,7 @@ exclude: [
   Crowdin.yaml,
   staticman.yml,
   torrents,
+  _pages/*/include/
   _pages/af_ZA,
   _pages/ar_SA,
   _pages/bg_BG,

_pages/en_US/include/install-boot9strap-safeb9sinstaller.txt

@@ -0,0 +1,9 @@
+In this section, you will install custom firmware onto your device.
+
+1. When prompted, input the key combo given on the top screen to install boot9strap
+1. Once it is complete, press (A) to reboot your device
+1. Your device should have rebooted into the Luma3DS configuration menu
+  + Luma3DS configuration menu are settings for the Luma3DS custom firmware. Many of these settings may be useful for customization or debugging
+  + For the purpose of this guide, these settings will be left on default settings
+  + If your device shuts down when you try to power it on, ensure that you have copied `boot.firm` from the Luma3DS `.zip` to the root of your SD card
+1. Press (Start) to save and reboot

_pages/en_US/installing-boot9strap-(hbl-usm).txt

@@ -71,16 +71,7 @@ In this section, you will enter Safe Mode (a feature available on all 3DS family
 
 #### Section III - Installing boot9strap
 
-In this section, you will install custom firmware onto your device.
-
-1. When prompted, input the key combo given on the top screen to install boot9strap
-  + If the top screen is blank, power off your device and re-do Section III
-1. Once it is complete, press (A) to reboot your device
-1. Your device should have rebooted into the Luma3DS configuration menu
-  + Luma3DS configuration menu are settings for the Luma3DS custom firmware. Many of these settings may be useful for customization or debugging
-  + For the purpose of this guide, these settings will be left on default settings
-  + If your device shuts down when you try to power it on, ensure that you have copied `boot.firm` from the Luma3DS `.zip` to the root of your SD card
-1. Press (Start) to save and reboot
+{% include_relative include/install-boot9strap-safeb9sinstaller.txt %}
 
 At this point, your console will boot to Luma3DS by default.
   + Luma3DS does not look any different from the normal HOME Menu. If your console has booted into the HOME Menu, it is running custom firmware.

_pages/en_US/installing-boot9strap-(kartdlphax).txt

@@ -128,16 +128,7 @@ In this section, you will enter Safe Mode (a feature available on all 3DS family
 
 #### Section V - Installing boot9strap
 
-In this section, you will install custom firmware onto your device.
-
-1. When prompted, input the key combo given on the top screen to install boot9strap
-  + If the top screen is blank, power off your device and re-do Section III
-1. Once it is complete, press (A) to reboot your device
-1. Your target 3DS should have rebooted into the Luma3DS configuration menu
-  + Luma3DS configuration menu are settings for the Luma3DS custom firmware. Many of these settings may be useful for customization or debugging
-  + For the purpose of this guide, these settings will be left on default settings
-  + If your device shuts down when you try to power it on, ensure that you have copied `boot.firm` from the Luma3DS `.zip` to the root of your SD card
-1. Press (Start) to save and reboot
+{% include_relative include/install-boot9strap-safeb9sinstaller.txt %}
 
 At this point, your console will boot to Luma3DS by default.
   + Luma3DS does not look any different from the normal HOME Menu. If your console has booted into the HOME Menu, it is running custom firmware.

_pages/en_US/installing-boot9strap-(soundhax).txt

@@ -76,14 +76,7 @@ In this section, you will launch Soundhax through the Nintendo 3DS Sound app, wh
 
 In this section, you will install custom firmware onto your device.
 
-1. When prompted, input the key combo given on the top screen to install boot9strap
-1. Once it is complete, press (A) to reboot your device
-1. Your device should have rebooted into the Luma3DS configuration menu
-  + Luma3DS configuration menu are settings for the Luma3DS custom firmware. Many of these settings may be useful for customization or debugging
-  + For the purpose of this guide, these settings will be left on default settings
-  + If your device shuts down when you try to power it on, ensure that you have copied `boot.firm` from the Luma3DS `.zip` to the root of your SD card
-1. Press (Start) to save and reboot
-  + If you get an error, just continue to the next page
+{% include_relative include/install-boot9strap-safeb9sinstaller.txt %}
 
 At this point, your console will boot to Luma3DS by default.
   + Luma3DS does not look any different from the normal HOME Menu. If your console has booted into the HOME Menu, it is running custom firmware.

_pages/en_US/installing-boot9strap-(ssloth-browser).txt

@@ -80,12 +80,7 @@ In this section, you will visit the browser exploit webpage, which will use univ
 
 In this section, you will install custom firmware onto your device.
 
-1. When prompted, input the key combo given on the top screen to install boot9strap
-1. Once it is complete, press (A) to reboot your device
-1. Your device should have rebooted into the Luma3DS configuration menu
-  + If your device shuts down when you try to power it on, ensure that you have copied `boot.firm` from the Luma3DS `.zip` to the root of your SD card
-1. Press (Start) to save and reboot
-  + If you get an error, just continue to the next page
+{% include_relative include/install-boot9strap-safeb9sinstaller.txt %}
 
 At this point, your console will boot to Luma3DS by default.
   + Luma3DS does not look any different from the normal HOME Menu. If your console has booted into the HOME Menu, it is running custom firmware.

_pages/en_US/installing-boot9strap-(usm).txt

@@ -86,16 +86,7 @@ In this section, you will enter Safe Mode (a feature available on all 3DS family
 
 #### Section IV - Installing boot9strap
 
-In this section, you will install custom firmware onto your device.
-
-1. When prompted, input the key combo given on the top screen to install boot9strap
-  + If the top screen is blank, power off your device and re-do Section III
-1. Once it is complete, press (A) to reboot your device
-1. Your device should have rebooted into the Luma3DS configuration menu
-  + Luma3DS configuration menu are settings for the Luma3DS custom firmware. Many of these settings may be useful for customization or debugging
-  + For the purpose of this guide, these settings will be left on default settings
-  + If your device shuts down when you try to power it on, ensure that you have copied `boot.firm` from the Luma3DS `.zip` to the root of your SD card
-1. Press (Start) to save and reboot
+{% include_relative include/install-boot9strap-safeb9sinstaller.txt %}
 
 At this point, your console will boot to Luma3DS by default.
   + Luma3DS does not look any different from the normal HOME Menu. If your console has booted into the HOME Menu, it is running custom firmware.