Doc: Improve accessibility of project gallery #615
Description
Problem
As more project got listed on https://zkmopro.org/docs/projects, it becomes difficult to access the projects with categories.
Details
Add tags and ctegory sections for better discoverability. Take https://semaphore.pse.dev/projects as an example.
Acceptance criteria
- Added proper tags for existing projects in the gallery
- Create category section for filtering