Make Add Tag less Contrasty

[theammaramin]

Hi! This is my first Pull Request.

I addressed Issue #851: Make "Add tag" text less contrasty.

Summary of changes:

• Increased the opacity of the "Add tag" text in add-tag.component.scss to reduce its contrast and better match the surrounding UI.

Let me know if any adjustments are needed. Thanks!

[whyboris]

Thank you for the contribution! The code looks good; I'll want to see it on my machine before I merge the commit, but I think this is sufficient 😁 (I'll glance if the dark mode needs any adjustments 👍 )

I'm likely to get to VHA work sometime in July-August this year 🤞 - the PR will hang around, but I won't forget 🙇‍♂️

Cheers!