Improve documentation about old Android and downloading documents

[bgstack15]

Is your feature request related to a problem? Please describe.
AndBible technically runs on an old version of Android, but will not successfully download documents from the main repositories. The issue appears to be the Let's Encrypt certs protecting andbible.org and similar sites. Old Android didn't trust the newer LE root (https://letsencrypt.org/2020/12/21/extending-android-compatibility/).

Describe the solution you'd like
Page https://github.com/AndBible/and-bible/wiki/FAQ#i-have-older-phone-that-doesnt-have-android-60-can-i-use-andbible can suggest to the user to install the Let's Encrypt root certificates on old Android so AndBible will download documents. Maybe link to https://knowledgebase.geolantis.com/HOW%20TO/how-to-install-root-certificate-on-android-6-0-device/ or duplicate its steps here.

Describe alternatives you've considered
Just link to https://knowledgebase.geolantis.com/HOW%20TO/how-to-install-root-certificate-on-android-6-0-device/

Additional context
This will make regular users' ability to use AndBible for the main purpose of viewing documents from these central repositories possible. I wouldn't expect an average Android user to know about the LE certs on the document repository.

However, this action installs root certificates on the device which can be a risk to users who might be in persecuted jurisdictions. Maybe add a big caveat about this affecting operations of the whole Android device.

[tuomas2]

Has all android 6's stopped working recently (i.e. downloading docs)? I haven't tried recently but I am not aware of that.

[timbze]

FYI #823 dealt with same issue.

[tuomas2]

So maybe the question is @bgstack15 which version of AndBible are you using? #823 was fixing the issue at that time.

[bgstack15]

Version 5.0.840#e5279fa45 fdroid standard release (built 07/01/25 17:08:05)
I definitely had the problem until I installed the Let's Encrypt roots.