Add description to spec:inputs

What does this MR do and why?

The changes in this merge request it to add a description field to inputs in GitLab CI/CD. This description field is optional and can be used to provide more information about the input. This MR is addressing following issue.

How to set up and validate locally

Update you .gitlab-ci.yml with following:

spec:
  inputs:
    test222:
      default: '0123dd456789'
      description: 'description'
---

test-job:
  script: echo test-job

Run validation or push up the code and see that the pipeline succeeded without errors.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.