item-title on Tags page should also be H2

MR: Update item-title on Tags page to h2 (!195560 - merged)

Summary

The main problem is that on the Tags page and individual Tag pages, the tag titles have the class "item-title" but lack proper HTML heading structure (H2 tags). Similarly, in the documentation example, multiple H1 tags are incorrectly used when they should be H3 tags. The desired outcome is to properly implement semantic HTML heading structure by adding H2 tags to tag titles and correcting the documentation example to use H3 instead of H1.

Requirements & Details

1. Tags on the Tags page and individual Tag pages should be marked up with H2 tags (in addition to the existing "item-title" class)
2. The example documentation at https://docs.gitlab.com/ce/workflow/releases.html should be corrected to use H3 tags (three hash signs) instead of multiple H1 tags
3. The issue exists on GitLab.com
4. A suggested fix is to wrap the same element that has the "item-title" class with an h2 tag

Steps to reproduce

Create Tags, visit the Tags page, or the page for an individual Tag

What is the current bug behavior?

The Tags themselves are not marked up with H2

What is the expected correct behavior?

The Tags marked up with H2

Output of checks

This bug happens on GitLab.com

Possible fixes

Wrap the same thing as item-title with h2