Improvements to wording in README

Co-authored-by: Danilo Bargen <mail@dbrgn.ch>

README.md

@@ -79,10 +79,12 @@ for example the `STM32L062K8Tx` uses the GPIO peripheral version named
 
 ## Flash memory
 
-Flash and RAM sizes are configured for each mcu in the feature list.
+Flash and RAM sizes are automatically configured by using the appropriate
+`mcu-*` Cargo feature, as described further up.
 
-If you have an mcu that is not in the list or they are not correct, you can override 
-the `memory.x` of `stm32l0xx-hal` by providing your own.
+If you have an MCU that does not yet have a corresponding `mcu-*` feature, or
+if the default configuration is incorrect, you can override the `memory.x` of
+`stm32l0xx-hal` by providing your own:
 In your crate root, add a file called `memory.x` with the correct configuration. For example:
 
 ```