Show registration period notes when registration period is active (#535)

What does this MR do?

button that displays a modal with the registration period notes on Courses Registration View

Related issues and links

Fix

Other relevant links

Developer Checklist

• My code runs successfully locally

• I have submit screenshots of the code running locally

• My code works in all necessary screen sizes

• I have tested my code with different users to spot bugs

• My code has appropriate names for variables and comments in English

• My branch is up-to-date with the upstream master branch

• Coding is in progress, and I have marked the MR as WIP

• My MR follows the contribution guidelines

• I have added a comment with screenshots of the code running locally

Tech review Checklist

Have you verified that what is supposed to happen, actually does, and what is not supposed to happen, indeed does not?

• The MR accurately describes the changes and has a relevant title/description
• The MR does what it is supposed to according to its title, description and related issues/links
• I have successfully run the changes locally, and tried the new code

Overall review Checklist

• The MR references related issues/MRs
• The MR provides links to screens and screenshots
• The commits of the MR describe the changes, have proper wording, and follow the guidelines
• I have successfully run the changes locally, and tried the new code
• The MR is ready for merge (rebased, commit squashed if needed, etc)