typo

Hardware-API.md

@@ -58,7 +58,7 @@ Conventions are:
 
 In the method specs below, *NOHEAP* means the function cannot allocate on the heap.  For some ports this may be difficult if the function needs to return an integer value that does not fit in a small integer.  Don't know what to do about this.
 
-## OSError exceptions regarding periherals
+## OSError exceptions regarding peripherals
 
 - In case that the peripheral is not available (invalid id) ??
 - Operations on non-initialized peripherals ??