feat: Append ModDescription not override it

[SlejmUr]

Description

Describe the changes
Changed the = to += to append into ModDescription not override it.

What is the current behavior? (You can also link to an open issue here)
Overriding any description that set before exiled.

What is the new behavior? (if this is a feature change)
Append after any change made to ModDescription before exiled run.

Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)
No

Other information:

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)
• Documentations

Submission checklist

• I have checked the project can be compiled
• I have tested my changes and it worked as expected

Patches (if there are any changes related to Harmony patches)

• I have checked no IL patching errors in the console

Other

• Still requires more testing

[louis1706]

Bruh i didn't seen it's was targeting master