Add AltStore installation instructions (#8)

* Adding the AltStore/SideStore source link

* Fix typo

* Rewrite text

---------

Co-authored-by: Skitty <mrskittyblock@gmail.com>

Author: OniriCorpe

content/help/guides/getting-started.md

@@ -18,9 +18,13 @@ Aidoku can be installed using TestFlight or through a service like AltStore that
 5. Download TestFlight from the App Store
 6. Install Aidoku from TestFlight after accepting the invitation
 
+### AltStore / SideStore source
+
+We have an AltStore source that contains the latest released build, which can be accessed by adding the following source link to AltStore or SideStore: [https://raw.githubusercontent.com/Aidoku/Aidoku/altstore/apps.json](https://raw.githubusercontent.com/Aidoku/Aidoku/altstore/apps.json). Please note that AltStore PAL is not supported.
+
 ### Manual Installation
 
-Compiled ipa files can be optained from the GitHub [releases](https://github.com/Aidoku/Aidoku/releases) page. If you're jailbroken, have AltStore already set up, or have another method of installation, this may be the simplest option, but also requires you to sideload a new ipa after every app update.
+Compiled ipa files can be optained from the GitHub [releases](https://github.com/Aidoku/Aidoku/releases) page. If you're jailbroken or have another method of sideloading, this may be the simplest option, but also requires you to sideload a new ipa after every app update.
 
 ### Troubleshooting