Add a note about tracking the versions in two different places

What does this MR do?

Unfortunately, we need to keep track of mobsf version in two different places. This note will remind me to update mobsf version in both places whenever needed.

What are the relevant issue numbers?

gitlab-org/security-products/release#106

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer