Add contribution guide (#884)

Author: SteveMutungi254

CONTRIBUTING.md

@@ -1,13 +1,92 @@
-# Contributing
+# Contributing to Microsoft Entra PowerShell
 
-When contributing to this repository, first open an issue describing the update you wish to make and read over our guidelines.
+This repository contains PowerShell cmdlets for developers and administrators to develop, deploy,
+administer, and manage Microsoft Entra product family resources.
 
-There are a few different recommended paths to get contributions into the released version.
+## Basics
+
+If you would like to become a contributor to this project (or any other open source Microsoft
+project), see how to [Get Involved](https://opensource.microsoft.com/collaborate/).
+
+## Before Starting
+
+### Onboarding
+
+All users must sign the
+[Microsoft Contributor License Agreement (CLA)](https://cla.opensource.microsoft.com/) before making
+any code contributions. For Microsoft employees, make sure that your GitHub account is part of the
+Microsoft Graph organization. [Use this page](https://repos.opensource.microsoft.com/) to link your account.
+
+### Code of Conduct
+
+This project adopts the
+[Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/). For more
+information, see the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or
+contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with any more questions or
+comments.
+
+### GitHub Basics
+
+#### GitHub Workflow
+
+The following guides provide basic knowledge for understanding Git command usage and the workflow of
+GitHub.
+
+- [Git Cheat Sheet](https://education.github.com/git-cheat-sheet-education.pdf)
+- [GitHub Flow](https://guides.github.com/introduction/flow/)
+
+#### Forking the microsoftgraph/entra-powershell repository
+
+Unless you're working with multiple contributors on the same file, we ask that you fork the
+repository and submit your pull request from there. The following guide explains how to fork a
+GitHub repo.
+
+- [Contributing to GitHub projects](https://guides.github.com/activities/forking/).
 
 ## Filing Issues
 
-The best way to get started with a contribution is to start a dialog with us. Sometimes, features are under development or out of scope for this module, and it's best to check before starting work on contribution, especially for large work items.
+You can find all of the issues filed for Microsoft Entra PowerShell in the
+[Issues](https://aka.ms/entra/ps/issues) section of this repository.
+
+To file an issue, select one of the
+[templates](https://github.com/microsoftgraph/entra-powershell/issues/new/choose). The template ensures that all of
+the necessary information is provided. The following are a few of the templates we provide:
+
+- [_Entra PowerShell module bug report_](https://github.com/microsoftgraph/entra-powershell/issues/new?assignees=&labels=ToTriage&projects=&template=entra-powershell-bug-report.md)
+- [_Feature request_](https://github.com/microsoftgraph/entra-powershell/issues/new?assignees=&labels=ToTriage&projects=&template=feature_request.md&title=%5BFeature%5D%3A+)
+
+You can find the code complete and release dates of the upcoming Entra PowerShell releases in the
+[Milestones](https://github.com/microsoftgraph/entra-powershell/milestones) section of the _Issues_ page.
+Each milestone displays the issues that are being worked on for the corresponding release.
+
+## Submitting Changes
+
+### Pull Requests
+
+You can find all of the pull requests that opened in the
+[Pull Requests](https://github.com/microsoftgraph/entra-powershell/pulls) section of this repository.
+
+When creating a pull request, keep the following in mind:
+
+- Verify you're pointing to the fork and branch that your changes were made in.
+- Choose the correct branch you want your pull request to be merged into.
+  - The **main** branch is for active development; changes in this branch will be in the next Entra
+    PowerShell release.
+- The pull request template that is provided **must be filled out**. Don't delete or ignore it when
+  the pull request is created.
+  - **_IMPORTANT:_** Deleting or ignoring the pull request template delays the PR review process.
+- The SLA for reviewing pull requests is **three business days**.
+
+### Pull Request Guidelines
+
+A pull request template will automatically be included as a part of your PR. Fill out the
+checklist as specified. Pull requests **will not be reviewed** unless they include a properly
+completed checklist.
+
+#### Testing guidelines
 
-## Improving Commands
+The following guidelines must be followed in **every** pull request that is opened.
 
-This module provides a customization logic that helps us to manually improve the autogenerated code, adding missing Commands, missing parameters on Commands, and missing output values. Check the customization guidelines.
+- Changes made have corresponding test coverage.
+- Tests shouldn't include any hardcoded values, such as DisplayName, resource ID, etc.
+- No existing tests should be skipped.