Mention processEntireQueue instead of processQueue for one-off indexing

[alexbudarov]

Environment

• Existing page: https://doc.cuba-platform.com/fts-7.2/qs_project_setup.html

Description of the bug or enhancement

https://www.cuba-platform.com/discuss/t/fts-addon-entity-not-indexed/13945/2

Users are misguided. Manual mentions that for one-off indexing:

consequently invoke reindexAll() first and then processQueue()

This is wrong, processQueue() indexes only one batch.