Fix docs typo geterr_clear -> giterr_clear

docs/error-handling.md

@@ -128,7 +128,7 @@ The public error API
   bugs, but in the meantime, please code defensively and check for NULL
   when calling this function.
 
-- `void geterr_clear(void)`: This function clears the last error.  The
+- `void giterr_clear(void)`: This function clears the last error.  The
   library will call this when an error is generated by low level function
   and the higher level function handles the error.