Review lag for DSEW-CPR

[krivard]

Our API docs for DSEW-CPR claim that lag varies due to weekend effects, but the file I have labeled 20220131 (a Monday) has the same lag as the file I have labeled 20220202 (a Wednesday). This suggests that the lag behavior for this indicator is either uniform, or dependent on something other than the stated date for each source file. We should figure out which, and clarify the documentation:

delphi-epidata/docs/api/covidcast-signals/dsew-cpr.md

Line 59 in a406a8a

Hospital admissions are reported with a lag of 2 days, but since the CPR is not updated on weekends, lag effectively varies from 2-4 days.