DOC: add examples BusinessMonthEnd(0) and SemiMonthEnd(0)
This PR is related to PR #49958.
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Updated docs for `BusinessMonthEnd` and `SemiMonthEnd`. Added more examples to highlight “the last day of the month” behavior. Gave examples that use the parameter n equals 0.
Hi, @MarcoGorelli, I updated docs for `BusinessMonthEnd` and `SemiMonthEnd`. To clarify  “the last day of the month” behavior I added examples with `n=0`. Could you please take a look at my PR?