[Doc] Minor formatting fix in JSS Server Setup documentation

[Steve0x43]

Description

• Fixes minor formatting issue on XML code snippet within JSS Server Setup documentation (see step 4):

• Corrects capitisation of 7-Zip.
• Highlights Web.config with code formatting.

Motivation

Improves documentation quality.

How Has This Been Tested?

Tested locally; visually validated change worked as expected.

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 (non-breaking change; modified files are limited to the /docs directory)

Checklist:

• I have read the Contributing guide.
• My code follows the code style of this project.
• My code/comments/docs fully adhere to the Code of Conduct.
• My change is a code change and it requires an update to the documentation.
• My change is a documentation change and it requires an update to the navigation.