Rename add-on MCP -> developer MCP in several instances in the setup documentation

[bharatr21]

Description

Replace outdated instances of "Adobe Express Add-ons MCP" with the latest "Adobe Express Developer MCP"

Related Issue

Motivation and Context

The same documentation has an info/warning box stating the rename, but that does not stand out for users setting up the tool and more over, it is not up to date with the subsequent screenshot showing adobe-express-developer should be connected.

How Has This Been Tested?

Tested it with GitHub's built in markdown previewer

Screenshots (if appropriate):

Types of changes

Changes to documentation

• 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)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes. (Not required)
• All new and existing tests passed.