Update map-generator readme (output files & tile count) (#2709)

## Description:

- clarify the map generator readme size recommendation is for land tile
count, not px size (and that it is for performance, not a hard limit).
Add note about average map land tile count to provide more context.
- Add output files list to provide reference for where to find land tile
count (for some reason the script doesn't output it, will probably open
a new PR to add it to the output of the generator)

I must have missed some context when first documenting this, oops!

## Please complete the following:

- [X] I have added screenshots for all UI updates
- [X] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [X] I have added relevant tests to the test directory
- [X] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

tidwell

map-generator/README.md

@@ -33,6 +33,14 @@ To process a subset of maps, pass a comma-separated list:
 
 `go run . --maps=northamerica,world`
 
+## Output Files
+
+- `../resources/maps/<map_name>/manifest.json` - JSON metadata containing map dimensions and land tile counts for all scales.
+- `../resources/maps/<map_name>/map.bin` - Full-scale binary map data packed with terrain type and magnitude.
+- `../resources/maps/<map_name>/map4x.bin` - 1/4 scale (half dimensions) binary map data used for mini-maps.
+- `../resources/maps/<map_name>/map16x.bin` - 1/16 scale (quarter dimensions) binary map data used for mini-maps.
+- `../resources/maps/<map_name>/thumbnail.webp` - WebP image thumbnail of the map.
+
 ## Create image.png
 
 The map-generator will process your input file at `assets/maps/<map_name>/image.png` to generate the map
@@ -105,11 +113,16 @@ Using the `name` from your json:
 
 ## Notes
 
-- Maps should be between 2 - 3 million pixels square (area)
 - Islands smaller than 30 tiles (pixels) are automatically removed by the script.
 - Bodies of water smaller than 200 tiles (pixels) are also removed.
 - The map generator normalizes dimensions to multiples of 4. Any pixels beyond `Width - (Width % 4)` or `Height - (Height % 4)` are cropped.
 
+For Performance Reasons:
+
+- Maps should be between 2 - 3 million pixels square (area).
+- Maps with over 3 million land tiles are not recommended.
+- Average land tile count is around 1 - 2 million.
+
 ## 🛠️ Development Tools
 
 - **Format map-generator code**: