Update README.template.md

Author: ocots

README.template.md

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 # CTBase.jl
 
+<!-- 
+For instructions on how to customize this README.template.md and use the centralized workflow,
+please see the user guide: https://github.com/orgs/control-toolbox/discussions/67
+-->
+
 The CTBase.jl package is part of the [control-toolbox ecosystem](https://github.com/control-toolbox).
 
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