Updating README: Adding downloads [skip ci]

Author: James Brundage

README.md

@@ -4,6 +4,7 @@
 
 PowerShell Tools for DevOps
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+[![Gallery Downloads](https://img.shields.io/powershellgallery/dt/PSDevOps)](https://www.powershellgallery.com/packages/PSDevOps/)
 [![Build Status](https://dev.azure.com/StartAutomating/PSDevOps/_apis/build/status/StartAutomating.PSDevOps?branchName=master)](https://dev.azure.com/StartAutomating/PSDevOps/_build/latest?definitionId=5)
 [![Build Status](https://github.com/StartAutomating/Irregular/actions/workflows/IrregularTests.yml/badge.svg)](https://github.com/StartAutomating/PSDevOps/actions/workflows/TestAndPublish.yml)
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