Clean up OLED last character printing

[josephscampo]

Description

On the corne OLED, there is a line which prints the last keystroke logged. As not all keystroke strings are equal in length, if keystroke N prints a shorter line than keystroke N-1, then the printed line on the OLED screen will have a few nonsensical characters at the end. My change prints a newline at the end of the keystroke log, so that any stale characters are cleared.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• 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.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[josephscampo]

switched to advance page, thanks for the tip @drashna. tested on my kbd 👍

[fauxpark]

Please remove your personal keymaps from this PR.

personal keymaps included in pr