component/macros/virtual-env: Add a readme to use the macro

2 jobs for custom-virtual-env
Status Job ID Name Coverage
  External
running SlapOS.SoftwareReleases.IntegrationTest-TleymoneCustom.Virtual.Env

20552:04:33

running SlapOS.SoftwareReleases.IntegrationTest-TleymoneCustom.Virtual.Env.Py3

20552:04:31