esp32/README: Add hint about using GNUmakefile on case-insensitive FS.
@@ -65,6 +65,8 @@ include Makefile
```
Be sure to enter the correct path to your local copy of the IDF repository
(and use `$(HOME)`, not tilde, to reference your home directory).
+If your filesystem is case-insensitive then you'll need to use `GNUmakefile`
+instead of `makefile`.
If the Xtensa cross-compiler is not in your path you can use the
`CROSS_COMPILE` variable to set its location. Other options of interest
are `PORT` for the serial port of your esp32 module, and `FLASH_MODE`
