message: doc(c-api) Fix a typo.
diff: @@ -43,8 +43,8 @@ is owned by the caller.
  The `wasm.h` header does not say anything about null pointer. The
  behavior we agreed on in that passing a null pointer where it is not
  -expected (i.e. no where) will make the function to return null too
  -without any error.
  +expected (i.e. everywhere) will make the function to return null too
  +with no error.
  ### Rust Pattern
  