Add supported iOS versions to Readme

[Darthagnon]

Describe the bug
There is no easy indication of what iOS versions are supported for this app. Please can this info be added to the README?

Currently listed in\Antidote_unsigned_v1.4.28.ipa\Payload\Antidote.app\Info.plist, MinimumOSVersion is 11.0

I have tried manually editing this to 7.0, but installation fails on my iOS 7.1.2 iPhone 4S (Coolboot/Jailbroken). It's possible compilation with an older version of XCode would allow it to work on older machines and iOS versions, though I'm guessing it is 64bit only (iPhone 4S is 32bit).

Expected behavior
A clear and concise description of what you expected to happen.

Your system information:

• Antidote Version: 1.4.28
• App from Github Releases
• IOS Version: iOS 7.1.2 Coolboot Jailbroken
• Device: iPhone 4S