New reverse zone: pick from the networks your records use, sized around them

The Zones page's New reverse zone lists every network the records use without a reverse zone, in every view, also where nothing is suggested (suggestions off, dismissed, public views), marked. Picking one fills in the network and view; size buttons (/48 /56 /64 /128, /16 /24 /32) re-mask it around a record's address, so a /48 becomes the records' own /64. Fill stays on. jarl zone suggest-reverse --all [--view V]; GET /reverse-zones/suggestions?all=1&view=.

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

docs/reverse.md

@@ -66,6 +66,25 @@ remembers, per view (`--undismiss` brings one back).
 Loopback and link-local addresses, wildcards and disabled records are left
 out.
 
+## Creating one by hand
+
+Where nothing is suggested (a view with suggestions off, a dismissed
+network, a public view) or the suggested size isn't the one you want,
+**New reverse zone** on the Zones page lists every network your records
+use that has no reverse zone, in every view, marked when it isn't
+suggested unasked. Pick one: the network and the view are filled in.
+Then the **Size** buttons change it, around the address of one of the
+records: a suggested `2a02:8013:7f3d::/48` becomes
+`2a02:8013:7f3d:10::/64` for the subnet the records are in, or `/128`
+for one address. The zone name shows as you go, and **PTR records** stays
+ticked, so the zone is created with a PTR record for each address
+(IPv6 nibble names written for you).
+
+```sh
+jarl zone suggest-reverse --all --view vps                     # every network, hidden ones marked
+jarl zone create 2a02:8013:7f3d:10::/64 --view internal --fill
+```
+
 ## Creating and filling
 
 ```sh