Pull request: openapi: fix more docs issues

Merge in DNS/adguard-home from fix-openapi to master

Squashed commit of the following:

commit bd95a502666372443b937cbcb690e307cd943342
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Jan 14 13:23:37 2021 +0300

    openapi: fix more docs issues

scripts/hooks/pre-commit

@@ -11,3 +11,8 @@ if [ "$(git diff --cached --name-only -- '*.go' 'go.mod')" ]
 then
 	make go-lint go-test
 fi
+
+if [ "$(git diff --cached --name-only -- './openapi/openapi.yaml')" ]
+then
+	make openapi-lint
+fi