Update README.md

Adding Incubation disclaimer to the README as per Project Lifecycle requirements 

Signed-off-by: Sophie Trinder <[email protected]>

README.md

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+### _[!important] Incubation Project : This project is an incubation project being run inside the Green Software Foundation; as such, we DON’T recommend using it in any critical use case. Incubation projects are experimental, offer no support guarantee, have minimal governance and process, and may be retired at any moment. This project may one day Graduate, in which case this disclaimer will be removed._
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 # carbon_ci_pipeline_tooling
 
 > Calculate the carbon emissions of an application via static analysis of the code and any infrastructure as code files in a repository.