Update gutters docs

[ChellyAhmed]

Description

In Bootstrap documentation, in Layout => Gutters. In the Horizontal & vertical gutters section, I changed the description from ".g-* classes can be used to control the horizontal gutter widths" to ".g-* classes can be used to control the horizontal and vertical gutter widths".

Motivation & Context

The documentation was misleading. In fact, the classes in question are used to modify horizontal and vertical gutters. However, it indicates that they only change the horizontal section. This might lead users, especially new ones, to confuse the classes "g-" with "gx-"

I thought of introducing these changes after checking issue #37914 opened by marcomarsala.

Type of changes

Documentation update

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would change existing functionality)

Live preview:

https://deploy-preview-37918--twbs-bootstrap.netlify.app/docs/5.3/layout/gutters/

Checklist

• I have read the contributing guidelines
• My code follows the code style of the project (using npm run lint)
• My change introduces changes to the documentation
• I have updated the documentation accordingly

Related issues

#37914