docs(template): add breaking change section (#5226)

* docs(template): add breaking change section

* docs(template): update readme.md

* docs: add contributing section for templates

* docs(tempalte): rename document

Author: hund030

CONTRIBUTING.md

@@ -21,6 +21,7 @@ For contributing to different packages, find the instructions below:
 - [Contributing to Function Extension](https://github.com/OfficeDev/TeamsFx/blob/main/packages/function-extension/CONTRIBUTING.md)
 - [Contributing to Simple Auth](https://github.com/OfficeDev/TeamsFx/blob/main/packages/simpleauth/CONTRIBUTING.md)
 - [Contributing to .NET SDK](https://github.com/OfficeDev/TeamsFx/blob/main/packages/dotnet-sdk/CONTRIBUTING.md)
+- [Contributing to Scaffolding Template](https://github.com/OfficeDev/TeamsFx/blob/main/templates/CONTRIBUTING.md)
 
 # Code of Conduct
 

packages/fx-core/src/common/template-utils/readme.md templates/CONTRIBUTING.md

@@ -20,6 +20,28 @@ To scaffold from alpha release templates, set `TEAMSFX_TEMPLATE_PRERELEASE=alpha
   ```
 2. In cd pipeline, all templates in the list will be zipped and be released to GitHub.
 
+3. If your new template can not be scaffolded by older version Teams Toolkit, you need to commit your changes with a `BREAKING CHANGE` footer. The body of the footer has to be multi-line and the footer line must start with `BREAKING CHANGE:`
+```
+$ git add .
+
+$ git commit -m "feat(tab): upgrade react-scirpts
+BREAKING CHANGE: drop support for Node 12"
+
+$ git push
+```
+
+Some breaking change cases:
+
+* Involve new placeholder in templates.
+* Upgrade template's dependencies which deprecates support to lower version NodeJs. Latest Teams Toolkit notices users to upgrade their environment but older version Teams Toolkit does not.
+* Remove or rename templates.
+
+Cases that are not breaking changes:
+
+* Add new templates that old Teams Toolkit does not have entry to get and scaffold them.
+* Add new features to templates that does not require any change in Teams Toolkit.
+* Totally rewrite a template but old Teams Toolkit can still work with it.
+
 ## How to debug templates?
 
 1. Set `TEAMSFX_DEBUG_TEMPLATE=true` to your environment variables.