Add workflow_call to actions workflow example

[mschoettle]

Allows the workflow to be called from another workflow.

I copied the given example into its own workflow inside our .github repository of our organization. Calling it from another workflow didn't work because workflow_call was missing.

Not necessary, but could be nice to have this in the example.

[mschoettle]

/cc @mxmehl @carmenbianca

[mbtools]

Might as well add workflow_dispatch so we can trigger it manually 😃

[JaclynCodes]

This pull request makes a minor update to the workflow documentation in README.md to allow the lint workflow to be triggered by reusable workflow calls.

• Documentation update: The workflow trigger in the example .yml file now includes workflow_call, enabling the workflow to be invoked by other workflows.
  React.app.txt
  Google Gemini.md
  index.html