Improving installer scripts

[joeabbey]

- What I did Updated README.md with improved scripts.

- How I did it I used vim to edit README.md ... (Also tried the scripts in bash, dash, and zsh on macOS)

- How to verify it Try the scripts!

- Description for the changelog Install script which works for both Linux macOS Made a rough attempt at a Windows powershell script... publishing a docker-app-windows.tar.gz makes it somewhat awkward.

- A picture of a cute animal (not mandatory but encouraged)

[GordonTheTurtle]

Please sign your commits following these rules: https://github.com/moby/moby/blob/master/CONTRIBUTING.md#sign-your-work The easiest way to do this is to amend the last commit:

$ git clone -b "install-one-liners" git@github.com:joeabbey/app.git somewhere
$ cd somewhere
$ git commit --amend -s --no-edit
$ git push -f

Amending updates the existing PR. You DO NOT need to open a new one.

[codecov[bot]]

Codecov Report

Merging #450 into master will increase coverage by 0.04%. The diff coverage is n/a.

@@            Coverage Diff            @@
##           master    #450      +/-   ##
=========================================
+ Coverage   62.65%   62.7%   +0.04%     
=========================================
  Files          49      49              
  Lines        2362    2362              
=========================================
+ Hits         1480    1481       +1     
+ Misses        679     678       -1     
  Partials      203     203

Impacted Files	Coverage Δ
types/parameters/parameters.go	93.65% <0%> (+1.58%)	:arrow_up:

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