docs: Update architecture diagram host label

[KajiyamaVK]

Within the graph, just added a space so the title can be visible.

Motivation and Context

The title wasn't being shown entirely and the example shown in the graph was the same described in the text above. The example was causing the title to not be visible and was just adding a redundant info.

How Has This Been Tested?

Using mintlify, just checked visualy.

Breaking Changes

n/a

Types of changes

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

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context