doc: README update with new functionalities

[rulasg]

as a developer that uses the library
I need a readme that guides me how to use the library
to save time considering and using the library

• Rename to low case all docs as it will fail on linux
• Update reference on testinghelper-action to better explain the action as a tool of the module

[rulasg]

`
PSTOPIC
about_DemoPsModule

SHORT DESCRIPTION
DemoPsModule will help as a sample module to learn how to set Posh modules with multiple files.

LONG DESCRIPTION
DemoPsModule will help as a sample module to learn how to set Posh modules with multiple files.

This module scaffolding is based on TestingHelper module
    https://www.powershellgallery.com/packages/TestingHelper

DETAILED DESCRIPTION
This Module is a testing module to learn how to set Posh modules with multiple files.

This best practices is following Warrne F blog:
     http://ramblingcookiemonster.github.io/Building-A-PowerShell-Module/

Module folder structure
/ModuleName/
    Module      - DemoPsModule.psd1
                - DemoPsModule.psm1
                - public
                    - publicFunctions.ps1
                - private
                    - privateFunctions.ps1

    Testing     - DemoPsModuleTest
                    - DemoPsModuleTest.psd1
                    - DemoPsModuleTest.psm1
                        - private
                        - public
                           - publicFunctions.Tests.ps1
                    - test.ps1
                    - .vscode
                        - launch.json

    Deploy      - deploy.ps1
                - deploy-helper.ps1
    
    Sync        - sync.ps1
                - sync-helper.ps1

    DevCont     - .devcontainer
                    - devcontainer.json

    Release     - release.ps1
                - release-helper.ps1        

    About       - en-US
                    - about_DemoPsModule.help.txt

    License     - LICENSE
    ReadMe      - README.md

    Workflows   - .github
                - workflows
                    - powershell.yml
                    - deploy_module.yml
                    - test_with_TestingHelper.yml

`