Pull request: 1947 disable autohosts option

Merge in DNS/adguard-home from 1947-hosts-opt to master

Updates #1947.
Updates #2829.

Squashed commit of the following:

commit d09285c
Merge: cff8c4c 7c6557b
Author: Eugene Burkov <[email protected]>
Date:   Mon Apr 12 18:23:20 2021 +0300

    Merge branch 'master' into 1947-hosts-opt

commit cff8c4c
Author: Eugene Burkov <[email protected]>
Date:   Mon Apr 12 17:46:19 2021 +0300

    home: fix help

commit 1fa01d5
Author: Eugene Burkov <[email protected]>
Date:   Mon Apr 12 17:40:48 2021 +0300

    home: fix option order

commit 9d83cb6
Author: Eugene Burkov <[email protected]>
Date:   Mon Apr 12 17:28:30 2021 +0300

    aghnet: add important todo

commit 7f1386f
Author: Eugene Burkov <[email protected]>
Date:   Mon Apr 12 17:17:17 2021 +0300

    all: correct naming

commit cbe2b2e
Author: Eugene Burkov <[email protected]>
Date:   Mon Apr 12 15:55:46 2021 +0300

    all: mv functionality from util

commit e82ad53
Author: Eugene Burkov <[email protected]>
Date:   Mon Apr 12 15:41:35 2021 +0300

    home: imp code, docs

commit 9058977
Author: Eugene Burkov <[email protected]>
Date:   Mon Apr 12 15:02:34 2021 +0300

    home: add an option to disable autohosts

CHANGELOG.md

@@ -15,6 +15,8 @@ and this project adheres to
 
 ### Added
 
+- New flag `--no-etc-hosts` to disable client domain name lookups in the
+  operating system's /etc/hosts files ([#1947]).
 - The ability to set up custom upstreams to resolve PTR queries for local
   addresses and to disable the automatic resolving of clients' addresses
   ([#2704]).
@@ -54,6 +56,7 @@ and this project adheres to
 
 [#1273]: https://github.com/AdguardTeam/AdGuardHome/issues/1273
 [#1401]: https://github.com/AdguardTeam/AdGuardHome/issues/1401
+[#1947]: https://github.com/AdguardTeam/AdGuardHome/issues/1947
 [#2385]: https://github.com/AdguardTeam/AdGuardHome/issues/2385
 [#2393]: https://github.com/AdguardTeam/AdGuardHome/issues/2393
 [#2412]: https://github.com/AdguardTeam/AdGuardHome/issues/2412