Merge in GO/dnsproxy from 333-opt-timeout to master

Closes #333.

Squashed commit of the following:

commit f049d5e64d92635bb63fdb2e9cf73c97416df198
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Jun 13 16:54:26 2023 +0300

    main: imp docs, code

commit 627ed3b9399f94d67caf33cc86cc354375b38536
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Jun 13 16:22:04 2023 +0300

    main: rm short form, consider for local

commit d46aa0016929ada0968588f9a4fb0719ed046d40
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Jun 13 13:58:21 2023 +0300

    main: upd docs

commit 641cc9265f6e59b8dd6f9c6fac2f3aea4adbab28
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Jun 13 13:38:28 2023 +0300

    main: configurable timeout