docs: add font generation commands to builtin font headers (#547)

## Summary

* **What is the goal of this PR?** Simple quality of life, ease
maintenance
* **What changes are included?**
Update fontconvert.py to include the command used to generate each font
file in the header comment, making it easier to regenerate fonts when
needed.

I plan on adding options to this scripts (kerning, and maybe ligatures),
thus knowing which command was used, even with already existing options
like `--additional-intervals`, is important.

---

### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? _**NO**_

lib/EpdFont/builtinFonts/notosans_18_regular.h

@@ -3,6 +3,7 @@
  * name: notosans_18_regular
  * size: 18
  * mode: 2-bit
+ * Command used: fontconvert.py notosans_18_regular 18 ../builtinFonts/source/NotoSans/NotoSans-Regular.ttf --2bit
  */
 #pragma once
 #include "EpdFontData.h"