Change hyphen to ASCII character (#410)

Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
diff --git a/History.txt b/History.txt
index 901b6ad..231190f 100644
--- a/History.txt
+++ b/History.txt
@@ -19,7 +19,7 @@
 	  configIDLE_SHOULD_YIELD is set to 0.

 	+ ARMv8-M secure-side port:  Tasks that call secure functions from the

 	  non-secure side of an ARMv8-M MCU (ARM Cortex-M23 and Cortex-M33) have two

-	  contexts – one on the non-secure side and one on the secure-side. Previous

+	  contexts - one on the non-secure side and one on the secure-side. Previous

 	  versions of the FreeRTOS ARMv8-M secure-side ports allocated the structures

 	  that reference secure-side contexts at run time.  Now the structures are

 	  allocated statically at compile time.  The change necessitates the