John

Fixes the misuse of "a" vs "an", according to English grammatical expectations and using https://www.a-or-an.com/

Before submitting a PR please make sure that: 1. You have discussed your solution in an issue and have got an approval from a maintainer. See our [contribution guide](https://github.com/AdguardTeam/AdGuardHome/blob/master/CONTRIBUTING.md). 2....