Add to docstrings HourEnding and HourBegining have default inclusivity

[oxinabox]

To me it seems like a natural assumption that
HourEnding would have inclusivity of false, true,
and HourBeginning would have inclusivity of true, false

but I am not sure if I am typical or not.

[nickrobinson251]

Makes sense to me. And isn't it already the case?

julia> using Intervals, Dates

julia> HourEnding(DateTime(2017, 02, 28, 06))
AnchoredInterval{-1 hour,DateTime}(2017-02-28T06:00:00, Inclusivity(false, true))

julia> HourBeginning(DateTime(2017, 02, 28, 06))
AnchoredInterval{1 hour,DateTime}(2017-02-28T06:00:00, Inclusivity(true, false))

(tmp.BCUQL3co) pkg> status Intervals
    Status `/private/var/folders/hx/1h0bbkfd18d4n1qrnwmrl4j00000gn/T/tmp.BCUQL3co/Project.toml`
  [d8418881] Intervals v0.5.1

[oxinabox]

we should add it to the docstrings....

[nickrobinson251]

yes, could be said in words

it is there in the examples

Intervals.jl/src/anchoredinterval.jl

Lines 33 to 58 in 6010f10

	julia> HourEnding(DateTime(2016, 8, 11, 2, 30))
	HourEnding{DateTime}(2016-08-11T02:30:00, Inclusivity(false, true))
	```
	The `HE` and `HB` pseudoconstructors round the input up or down to the nearest hour, as
	appropriate:
	```julia
	julia> HE(DateTime(2016, 8, 11, 2, 30))
	HourEnding{DateTime}(2016-08-11T03:00:00, Inclusivity(false, true))
	julia> HB(DateTime(2016, 8, 11, 2, 30))
	HourBeginning{DateTime}(2016-08-11T02:00:00, Inclusivity(true, false))
	```
	### Example
	```julia
	julia> AnchoredInterval{Hour(-1)}(DateTime(2016, 8, 11, 12))
	HourEnding{DateTime}(2016-08-11T12:00:00, Inclusivity(false, true))
	julia> AnchoredInterval{Day(1)}(DateTime(2016, 8, 11))
	AnchoredInterval{1 day, DateTime}(2016-08-11T00:00:00, Inclusivity(true, false))
	julia> AnchoredInterval{Minute(5)}(DateTime(2016, 8, 11, 12, 30), true, true)
	AnchoredInterval{5 minutes, DateTime}(2016-08-11T12:30:00, Inclusivity(true, true))