I.13: grammar and hint to `std::string_view` (#1443)

- "a C-style, zero-terminated strings" is wrong, it must be either "C-style, zero-terminated strings" or "a C-style, zero-terminated string"
- added hint to `std::string_view

CppCoreGuidelines.md

@@ -1962,8 +1962,8 @@ This `draw2()` passes the same amount of information to `draw()`, but makes the
 
 ##### Exception
 
-Use `zstring` and `czstring` to represent a C-style, zero-terminated strings.
-But when doing so, use `string_span` from the [GSL](#GSL) to prevent range errors.
+Use `zstring` and `czstring` to represent C-style, zero-terminated strings.
+But when doing so, use `std::string_view` or `string_span` from the [GSL](#GSL) to prevent range errors.
 
 ##### Enforcement