More README

Author: jepler

README.md

@@ -28,8 +28,18 @@ label = Label(font=MONO_9, text="Hi Mom!")
  * Add a reuse-recognized `.license` file for it
  * Add it to the `[FONTS]` section of `config.toml`
 
-Presently all fonts are genreated at the same range of sizes, `SIZES` in `config.toml`.
+Presently all fonts are generated at the same range of sizes, `SIZES` in `config.toml`. This restriction could be lifted if it's for a good reason.
 
 ## Variants
 
 Two variants of each font are generated: The ASCII variant with code points 32-126, and the full variant with all glyphs in the original font. The ASCII variant can be especially useful when flash space is at a premium.
+
+More variants could be added for a good reason; it should be configurable in config.toml and possibly be settable per font.
+
+## Font Sizing
+
+The font sizes in this bundle are in pixels.
+Or, to be more technically accurte, they are rendered at a resolution of 1 pixel = 1/72 inch = 1 point.
+If you follow the [directions on learn](https://learn.adafruit.com/custom-fonts-for-pyportal-circuitpython-display/use-otf2bdf) your font is rendered at a scale of 1 pixel = 1/100 inch = 0.72 points.
+This means the resulting font pixel sizes are 33-40% larger for the Learn guide instructions vs the fonts in this bundle.
+In any case, you will likely need to manually test font sizes until you find the best one for your application and display.