fixup! allow closing writer explicitly

fix typos

include/bw64/writer.hpp

@@ -80,7 +80,7 @@ namespace bw64 {
     /// required information, i.e. the final chunk sizes etc.
     ///
     /// It is recommended to call this before the destructor, to handle
-    /// excpetions. If it does throw, this object may be in an invalid state,
+    /// exceptions. If it does throw, this object may be in an invalid state,
     /// so do not try again without creating a new object.
     void close() {
       if (!fileStream_.is_open()) return;
@@ -102,7 +102,7 @@ namespace bw64 {
 
     /// destructor; this will finalise and close the file if it has not
     /// already been done, but it is recommended to call close() first to
-    /// handle excpetions
+    /// handle exceptions
     ~Bw64Writer() { close(); }
 
     /// @brief Get format tag