Document PERMISSION table handling in v4 migration guide

Signed-off-by: nscuro <nscuro@protonmail.com>

Author: nscuro

docs/guides/administration/migrating-from-v4.md

@@ -145,8 +145,8 @@ v4-migrator bootstrap \
   --target-pass
 ```
 
-After this, the target has the v5 schema but no rows.
-The migrator's later phases populate `PERMISSION`, `LICENSE`, `TEAM`, etc. directly from your v4 source.
+After this, the target has the v5 schema and a seeded `PERMISSION` catalog (the well-known set of v5 permissions).
+No other rows are written by bootstrap; the migrator's later phases populate `LICENSE`, `TEAM`, `USER`, and the rest from your v4 source.
 
 ### 2. Verify the target
 
@@ -162,7 +162,7 @@ v4-migrator verify \
 `verify` reads but never writes. On a freshly bootstrapped target with no staging present, expect:
 
 - Schema version `202605111028` reported `OK`.
-- All row count columns zero.
+- All row count columns **except for the v5 `PERMISSION` table** zero.
 - No probe entries.
 
 ### 3. Dry run
@@ -505,6 +505,8 @@ v4-migrator bootstrap --target-url ... --target-user ... --target-pass
 v4-migrator load      --target-url ... --target-user ... --target-pass
 ```
 
+`bootstrap` re-seeds the v5 `PERMISSION` catalog after applying the schema, so the rerun of `load` can resolve permission foreign keys without re-running `transform`.
+
 !!! warning
 
     Don't manually `TRUNCATE` individual v5 tables and re-run `load`.

docs/tutorials/rehearsing-the-v4-migration.md

@@ -147,7 +147,7 @@ Applying v5 Flyway schema up to 202605111028
 Bootstrap complete. Flyway head = 202605111028. Run 'extract' or 'run' next.
 ```
 
-After this, the target has the v5 schema but no rows.
+After this, the target has the v5 schema but no rows, **except in the `PERMISSION` table**.
 
 ## Verifying the empty target
 
@@ -180,7 +180,7 @@ Expected output:
   13 CHECK constraint(s) hold across 55 loaded table(s)
 ```
 
-If the schema version is anything else or any row count is non-zero,
+If the schema version is anything else or any row count is non-zero, **except in the `PERMISSION` table**,
 the rest of the rehearsal will not work.
 
 ## Dry-running the migration