Pull request: all: add depracation section to CHANGELOG.md, imp HACKING.md

Merge in DNS/adguard-home from doc-deprecated to master

Squashed commit of the following:

commit c189404164af25786eea83fcee635c497f0cfe00
Merge: 108097cda 1191a9acb
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Dec 25 13:40:11 2020 +0300

    Merge branch 'master' into doc-deprecated

commit 108097cda62866ea78a55b9ddbbba1fdc68cef09
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Dec 25 13:05:03 2020 +0300

    all: imp markup and wording

commit 05a630da77b9b8491ba07cd647d9379c63b9c64e
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Dec 24 20:57:43 2020 +0300

    all: add depracation section to CHANGELOG.md, imp HACKING.md

CHANGELOG.md

@@ -56,6 +56,13 @@ and this project adheres to
 [#2391]: https://github.com/AdguardTeam/AdGuardHome/issues/2391
 [#2394]: https://github.com/AdguardTeam/AdGuardHome/issues/2394
 
+### Deprecated
+
+- _Go_ 1.14 support.  v0.106.0 will require at least _Go_ 1.15 to build.
+- The `darwin/386` port.  It will be removed in v0.106.0.
+- The `"rule"` and `"filter_id"` fields in `GET /filtering/check_host` and
+  `GET /querylog` responses.  They will be removed in v0.106.0 ([#2102]).
+
 ### Fixed
 
 - Inability to set DNS cache TTL limits ([#2459]).

HACKING.md

@@ -70,6 +70,14 @@ The rules are mostly sorted in the alphabetical order.
     func TestType_Method_suffix(t *testing.T) { /* … */ }
     ```
 
+ *  Name parameters in interface definitions:
+
+   ```go
+   type Frobulator interface {
+           Frobulate(f Foo, b Bar) (r Result, err error)
+   }
+   ```
+
  *  Name the deferred errors (e.g. when closing something) `cerr`.
 
  *  No shadowing, since it can often lead to subtle bugs, especially with
@@ -172,10 +180,15 @@ The rules are mostly sorted in the alphabetical order.
  *  Put utility flags in the ASCII order and **don't** group them together.  For
     example, `ls -1 -A -q`.
 
- *  `snake_case`, not `camelCase`.
+ *  `snake_case`, not `camelCase` for variables.  `kebab-case` for filenames.
+
+ *  UPPERCASE names for external exported variables, lowercase for local,
+    unexported ones.
 
  *  Use `set -e -f -u` and also `set -x` in verbose mode.
 
+ *  Use `readonly` liberally.
+
  *  Use the `"$var"` form instead of the `$var` form, unless word splitting is
     required.