Pull request: 2280 dns timeout

Merge in DNS/adguard-home-wiki from 2280-upstream-timeout to master

Squashed commit of the following:

commit a705353c7305e73de810ab4541a283e17c868e16
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Sat Jun 12 19:20:42 2021 +0300

    Configuration: add upstream timeout field description
Eugene Burkov 2021-06-15 17:37:34 +03:00
parent 1f41358bb8
commit d1b144ada5

@ -242,6 +242,9 @@ Settings are stored in [YAML format](https://en.wikipedia.org/wiki/YAML), possib
- `cache_time` — Safe Browsing, Safe Search, Parental Control cache TTL
- `max_goroutines` — Max. number of parallel goroutines for processing incoming requests
- `ipset` — List of domain-ipset_name associations for adding IP addresses of the specified domain names to an ipset list. Syntax: `DOMAIN[,DOMAIN].../IPSET_NAME[,IPSET_NAME]...`. IPv4 addresses are added to an ipset list with `ipv4` family, IPv6 addresses - to `ipv6` ipset list. ipset list must exist. This setting is supported on Linux only. This feature is similar to `--ipset` in dnsmasq.
- `upstream_timeout` (**since v0.107.0**) — The timeout for querying
upstream servers. Zero value will be rewritten with default one which is
10s.
- `local_domain_name` (**since v0.106.0**) — The domain name that AdGuard
Home uses for known internal hosts. The default value, which is also set
when this value is empty, is `lan`. So, if you have a machine called