Change the file extension for better readability

[DEntis-T]

What this PR does / why we need it:

• Provides a better readability of the official readme.

Which issue(s) this PR fixes:

• CompuPhase's readme.

Fixes #

What kind of pull this is:

• [ ] A Bug Fix
• [ ] A New Feature
• [x] Some repository meta (documentation, etc)
• [ ] Other

Additional Documentation:

• Nothing yet, I'll update the comment if needed!