fix(templates): blog_meta category & tag classname (B)

[wesleyboar]

Description

Describe:

• Build classname with automated, required, recognizable "slug" instead of empty "count".
• Classname is blog-categories-__FOR_LOOP_COUNT__ instead of blog-categories-.

References

• fixes #710

Checklist

• [x] I have read the contribution guide
• [ ] Code lint checked via inv lint
• [ ] changes file included (see docs)
• [ ] Usage documentation added in case of new features
• [ ] Tests added

[wesleyboar]

I do not like this solution. I prefer #711.