[DOCS] Modify Arithmetic notations in all the docstrings.

[Jay-sanjay]

The reason why earlier "Integer" being mentioned in the OMOP CDM, is that we will not have cohorts or subject id's that are say, "1.5" or something like that. But yes, it is fair to have "1.0" as a float value but it should really be an integer in that case.

Yet, we think it is best to not say Integer but rather Float to prevent confusion if in-case someone wonders - why "1" might work for a cohort ID when "1.0" does not.
cc @TheCedarPrince Thanks :)