update required params

[cb-nsrinivasa]

provider, repository are not required params

  provider:
    description: 'SCM provider that is hosting the repository. For example github, bitbucket, gitlab or custom'
    default: "${{ cloudbees.scm.provider }}"
  repository:
    description: 'Repository name with owner. For example, actions/checkout. Alternatively if provider is custom then this is the clone URL of the repository'
    default: "${{ cloudbees.scm.repository }}"