docs(importer): point post-import glossary resync at glossary:bulk-resync (#1431)

docs(importer): point post-import glossary resync at glossary:bulk-resync (#1431)

scripts/importer/README.md still told readers to run the old queued
glossary:resync --remove-existing + queue:work pair, which the rest of the
codebase (import-tool's append/clean/local-glossary-sync) moved off of for
being O(spellings x translations) and taking hours on the full dataset.

Also documents why glossary:bulk-resync has no --remove-existing flag: it
fully recomputes each translation's spelling links via sync() every run, so
stale/deleted-spelling links are always dropped without an opt-in step,
unlike glossary:resync, which needs the flag as an explicit wipe.

Co-authored-by: Pascal HAVELANGE <havelangep@hotmail.com>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>