Merge in GO/dnsproxy from fix-208 to master

Squashed commit of the following:

commit b3cab493cd24f7c0c7f1125b581b106226f1cd28
Author: Andrey Meshkov <am@adguard.com>
Date:   Tue Jul 25 17:10:44 2023 +0300

    fix review comments

commit 594f6f865d7e49c32b5b87d6b91727f29246a41a
Author: Andrey Meshkov <am@adguard.com>
Date:   Tue Jul 25 16:39:35 2023 +0300

    Added installation instructions

commit a63e8fefaef892acf191e652e85f3d8e11940f00
Author: Andrey Meshkov <ameshkov@MacBook-Pro-de-Andrey.local>
Date:   Tue Jul 25 16:15:40 2023 +0300

    Added official Docker image for dnsproxy
    Closes #208