Update around inv

[hyrodium]

• Add docstring to inv(::Quaternion)
• Add methods to Base.://

Before this PR

julia> using Quaternions

julia> Quaternion(1,2,3,4) // Quaternion(5,6,7,8)
ERROR: MethodError: no method matching //(::Quaternion{Int64}, ::Quaternion{Int64})

Closest candidates are:
  //(::Number, ::Complex)
   @ Base rational.jl:79
  //(::AbstractArray, ::Number)
   @ Base rational.jl:82

After this PR

julia> using Quaternions

julia> Quaternion(1,2,3,4) // Quaternion(5,6,7,8)
Quaternion{Rational{Int64}}(35//87, 4//87, 0//1, 8//87)

This behavior is consistent with //(::Complex, ::Complex)

julia> complex(1,2) // complex(5,6)
17//61 + 4//61*im

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (89232ef) 100.00% compared to head (bfaf0c6) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #133   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines          162       164    +2     
=========================================
+ Hits           162       164    +2     

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[sethaxen]

Can you also bump the patch version for a release?