* Add integration test for SOA
* Add docs for SOA record
* MAINT: Rename SoaInfo to SoaDefaults.
gorename -v -from '"github.com/StackExchange/dnscontrol/v3/providers/bind".SoaInfo' -to SoaDefaults
* The old algorithm was very complex for no good reason.
* The new algorithm is simply: Use yymmdd00 or (previous serial number +1) whichever is bigger.
* github.com/miekg/dns
* Greatly simplify the logic for handling serial numbers. Related code was all over the place. Now it is abstracted into one testable method makeSoa. This simplifies code in many other places.
* Update docs/_providers/bind.md: Edit old text. Add SOA description.
* SOA records are now treated like any other record internally. You still can't specify them in dnsconfig.js, but that's by design.
* The URL for issue 491 was wrong in many places
* BIND: Clarify GENERATE_ZONEFILE message
