After SERVER-43119, our failpoints documentation is out of date.

1. On the Internal wiki page, references to MONGO_FAIL_POINT_PAUSE_WHILE_SET and MONGO_FAIL_POINT_BLOCK should be updated, those macros are gone now.

2. A comment in curop_failpoint_helpers.h mentions MONGO_FAIL_POINT_PAUSE_WHILE_SET.

3. Instructions for using fail points is spread across fail_point.h and fail_point_service.h