[Wiki] Add Safe Space to the list

[shuvashish76]

https://github.com/Kunzisoft/KeePassDX/wiki/File-Manager-and-Sync#file-manager-application

Safe Space is similar to Anemo (works very well but the project looks inactive), please check it out and add to the table list. Only supports Android 10 or newer.

See their FAQs, especially "Why should I use this app, XYZ app is better?"

[shuvashish76]

#1157 (comment)

@nain-F49FF806 's forked version now available on F-Droid : https://f-droid.org/packages/alt.nainapps.aer/ I think we should also replace Anemo with Aer.