Can't find "Windows Subsystem for Linux" feature to install Bash for Windows

I'm trying to create a GitHub page with Jekyll on Windows, but to do that I am told I need to install Bash on Ubuntu on Windows. Ok, fine, so I go to Bash's installation guide. My computer is 64 bit, Windows 10, build version 15063.296, which is above 14393, so I should have met the requirements.

However, when I follow the instructions, I can't find "Windows Subsystem for Linux (beta)" in Windows Features. What do I do?

Edit: Yes, I had Developer Mode enabled, even with it enabled it does not show up.

To install Windows Subsystem Linux, you have to enable Developer Mode in Settings App. So open Settings > Update & Security > For Developer > Developer Mode & select it to enable.

Or you may enable Developer Mode with registry tweak. Make registry script (.reg) with the following::

Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\AppModelUnlock]
"AllowAllTrustedApps"=dword:1
"AllowDevelopmentWithoutDevLicense"=dword:1

Then wait some time to download the developer package. Next, open the Control Panel, click “Programs”, and click “Turn Windows Features On or Off” under Programs and Features. Enable the “Windows Subsystem for Linux (Beta)” option in the list here and click “OK”. Alternatively install WSL with commands::

1. Command Prompt:

   DISM.exe /Online /Enable-Feature /All /FeatureName:Microsoft-Windows-Subsystem-Linux /NoRestart
   

2. Powershell:

   Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Windows-Subsystem-Linux
   

Then resrtart your system and you are good to go. From Windows 10 build 16215, it is no longer required to enable Developer Mode and beta tag was removed from WSL optional component. See Windows 10 Installation Guide for further details.