Mail reverse DNS check, what Jarl adds to named.conf, lists one per line

jarld checks the reverse DNS of the public zones' MX and SPF addresses as the internet sees it, every 6 hours (Exposure page, jarl exposure mail, jarl_mail_reverse_dns_ok). The Server options page, jarl option generated and GET /options/generated list what Jarl writes into named.conf by itself; stats.rate_limit_log turns off the query-errors logging. Option lists of three or more elements are shown one per line.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/concepts.md

@@ -48,6 +48,14 @@ overwritten. Jarl records a checksum of every file it writes and reports
 **drift** when a file changes behind its back. It then refuses to overwrite
 the file until you say so (`--force`, or `jarl resync --force`).
 
+Some of named.conf comes from Jarl itself rather than from your options:
+the include of keys.conf, the statistics channel and the logging
+statistics need, blocking's `response-policy` and policy zones, and the
+view keys at the front of each view's `match-clients`. The Server options
+page lists them under **Added by Jarl**, with why each is there and what
+turns it on or off (`jarl option generated`). Where you have a statement
+of your own (`logging`, `statistics-channels`), Jarl merges into it.
+
 Comments are part of the data model: zones, records, ACLs, views, keys and
 options can all carry a comment, and Jarl writes it into the generated file.
 Comments in imported zone files are kept.