Revert "Further improve htcondor.Schedd.history()'s documentation of its since parameter."
Revert "Further improve htcondor.Schedd.history()'s documentation of its since parameter."

This reverts commit b3a05ece212e5287d450fd5ebb1dd029f7007a20.

htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor