Updated Readme, added additional using Statements which I will cleanup later.
Added Search Interval based Insertion Sort
Also added Tests for this with Interval 5,3,1
Regular Insertion Sort uses Interval 1 between the check places

Therefore I will refactor the Insertion Sort implementation to use the interval based one with a default value of 1
I will also refactor the ShellSort to use internally the Interval based Insertion Sort, since it leads to less code duplication.
Refactored InsertionSort to use an Interval Parameter with a default of 1 instead of a constant interval.
Regular Insertion Sort uses Interval 1 for the check, therefore the default parameter is 1.

Also Refactored the ShellSort to use internally the Interval based Insertion Sort, since it leads to less code duplication.