Fix typos (#82)

* readme: fix typos

* makefile: fix typos in examples

Makefile

@@ -70,7 +70,7 @@ help all:
 	@echo ' '
 	@echo 'Examples:'
 	@echo '  make bluepill program'
-	@echo '  make module MODULE="usbd.a" CFLAGS="-mcpu=cotrex-m4" DEFINES="STM32L4 STM32L476xx USBD_VBUS_DETECT"'
+	@echo '  make module MODULE="usbd.a" CFLAGS="-mcpu=cortex-m4" DEFINES="STM32L4 STM32L476xx USBD_VBUS_DETECT"'
 
 cmsis: $(CMSISDEV)/ST
 
@@ -247,4 +247,4 @@ stm32f401xc: clean
 	@$(MAKE) demo STARTUP='$(CMSISDEV)/ST/STM32F4xx/Source/Templates/gcc/startup_stm32f401xc.s' \
 						LDSCRIPT='demo/stm32f401xc.ld' \
 						DEFINES='STM32F4 STM32F401xC USBD_SOF_DISABLED' \
-						CFLAGS='-mcpu=cortex-m4'						
+						CFLAGS='-mcpu=cortex-m4'						

readme.md

@@ -105,7 +105,7 @@ See [hardware.md](hardware.md) for details.
 ### Using makefile ###
 + to build library module
 ```
-make module MODULE=path/module.a DEFINES="mcu spcified defines" CFLAGS="cpu cpecified compiler flags"
+make module MODULE=path/module.a DEFINES="mcu specified defines" CFLAGS="cpu specified compiler flags"
 ```
 + to build demo
 ```