Update mxbuild docs

[VaniAnandamurthy]

Summary
Updates the MxBuild documentation to reflect the versioning schema changes introduced in Mendix 11.5.0.

Changes Made

• Added information about the new SemVer versioning pattern (major.minor.patch) starting from version 11.5.0
• Clarified that the build number (fourth element) is dropped in the new versioning schema
• Included concrete examples (11.5.0 and 11.6.0-beta.1) to illustrate standard and pre-release versions

Context
Starting with version 11.5.0, Mendix transitions from the previous versioning format (e.g., 11.0.0.9976) to a semantic versioning format without the build number (e.g., 11.5.0). This documentation update ensures users understand how to reference and download the correct MxBuild version.

Testing

• Reviewed markdown formatting
• Verified examples are accurate
• Ensured consistency with existing documentation standards

[CLAassistant]

All committers have signed the CLA.

[quinntracy]

@VaniAnandamurthy Will you be adding more content to this PR, or can it be marked as ready for review?